diff --git a/app/main.py b/app/main.py
index d903bf4..9dd2732 100644
--- a/app/main.py
+++ b/app/main.py
@@ -6,61 +6,214 @@
 # Written permission must be obtained from the author for commercial uses.
 ###########################################################################
 
-from Login import *
-from Article import *
-import Yaml
-from user_service import userService
-from account_service import accountService
+from WordFreq import WordFreq
+from wordfreqCMD import youdao_link, sort_in_descending_order
+from UseSqlite import InsertQuery, RecordQuery
+import pickle_idea, pickle_idea2
+import os
+import random, glob
+from datetime import datetime
+from flask import Flask, request, redirect, render_template, url_for, session, abort, flash, get_flashed_messages
+from difficulty import get_difficulty_level, text_difficulty_level, user_difficulty_level
+
 app = Flask(__name__)
 app.secret_key = 'lunch.time!'
 
-# 将蓝图注册到Lab app
-app.register_blueprint(userService)
-app.register_blueprint(accountService)
-
 path_prefix = '/var/www/wordfreq/wordfreq/'
-path_prefix = './'  # comment this line in deployment
-
+path_prefix = './' # comment this line in deployment
 
 def get_random_image(path):
-    '''
-    返回随机图
-    :param path: 图片文件(JPEG格式)，不包含后缀名
-    :return:
-    '''
     img_path = random.choice(glob.glob(os.path.join(path, '*.jpg')))
-
     return img_path[img_path.rfind('/static'):]
 
-
 def get_random_ads():
-    '''
-    返回随机广告
-    :return: 一个广告(包含HTML标签)
-    '''
     ads = random.choice(['个性化分析精准提升', '你的专有单词本', '智能捕捉阅读弱点，针对性提高你的阅读水平'])
     return ads + '。 <a href="/signup">试试</a>吧！'
 
+def total_number_of_essays():
+    rq = RecordQuery(path_prefix + 'static/wordfreqapp.db')
+    rq.instructions("SELECT * FROM article")
+    rq.do()
+    result = rq.get_results()
+    return  len(result)
+
+def load_freq_history(path):
+    d = {}
+    if os.path.exists(path):
+        d = pickle_idea.load_record(path)
+    return d
+
+def verify_user(username, password):
+    rq = RecordQuery(path_prefix + 'static/wordfreqapp.db')
+    rq.instructions_with_parameters("SELECT * FROM user WHERE name=? AND password=?", (username, password))
+    rq.do_with_parameters()
+    result = rq.get_results()
+    return result != []
+
+def add_user(username, password):
+    start_date = datetime.now().strftime('%Y%m%d')
+    expiry_date = '20211230'
+    rq = InsertQuery(path_prefix + 'static/wordfreqapp.db')
+    rq.instructions("INSERT INTO user Values ('%s', '%s', '%s', '%s')" % (username, password, start_date, expiry_date))
+    rq.do()
+
+    
+def check_username_availability(username):
+    rq = RecordQuery(path_prefix + 'static/wordfreqapp.db')
+    rq.instructions("SELECT * FROM user WHERE name='%s'" % (username))
+    rq.do()
+    result = rq.get_results()
+    return  result == []
+
+def get_expiry_date(username):
+    rq = RecordQuery(path_prefix + 'static/wordfreqapp.db')
+    rq.instructions("SELECT expiry_date FROM user WHERE name='%s'" % (username))
+    rq.do()
+    result = rq.get_results()
+    if len(result) > 0:
+        return  result[0]['expiry_date']
+    else:
+        return '20191024'
+    
+
+
+def within_range(x, y, r):
+    return x > y and abs(x - y) <= r 
+
+
+def get_article_title(s):
+    return s.split('\n')[0]
+
+
+def get_article_body(s):
+    lst = s.split('\n')
+    lst.pop(0) # remove the first line
+    return '\n'.join(lst) 
+
+def get_today_article(user_word_list, articleID):
+
+    rq = RecordQuery(path_prefix + 'static/wordfreqapp.db')
+    if articleID == None:    
+        rq.instructions("SELECT * FROM article")
+    else:
+        rq.instructions('SELECT * FROM article WHERE article_id=%d' % (articleID))
+    rq.do()
+    result = rq.get_results()
+    random.shuffle(result)
+    
+    # Choose article according to reader's level
+    d1 = load_freq_history(path_prefix + 'static/frequency/frequency.p')
+    d2 = load_freq_history(path_prefix + 'static/words_and_tests.p')
+    d3 = get_difficulty_level(d1, d2)
+
+    d = {}
+    d_user = load_freq_history(user_word_list)
+    user_level = user_difficulty_level(d_user, d3) # more consideration as user's behaviour is dynamic. Time factor should be considered.
+    random.shuffle(result) # shuffle list
+    d = random.choice(result)
+    text_level = text_difficulty_level(d['text'], d3)
+    if articleID == None:
+        for reading in result:
+            text_level = text_difficulty_level(reading['text'], d3)
+            factor = random.gauss(0.8, 0.1) # a number drawn from Gaussian distribution with a mean of 0.8 and a stand deviation of 1
+            if within_range(text_level, user_level, (8.0 - user_level)*factor):
+                d = reading
+                break
+            
+    s = '<div class="alert alert-success" role="alert">According to your word list, your level is <span class="badge bg-success">%4.2f</span>  and we have chosen an article with a difficulty level of <span class="badge bg-success">%4.2f</span> for you.</div>' % (user_level, text_level)
+    s += '<p class="text-muted">Article added on: %s</p>' % (d['date'])
+    s += '<div class="p-3 mb-2 bg-light text-dark">'
+    article_title = get_article_title(d['text'])
+    article_body = get_article_body(d['text'])
+    s += '<p class="display-3">%s</p>' % (article_title)
+    s += '<p class="lead">%s</p>' % (article_body)
+    s += '<p><small class="text-muted">%s</small></p>' % (d['source'])
+    s += '<p><b>%s</b></p>' % (get_question_part(d['question']))
+    s = s.replace('\n', '<br/>')    
+    s += '%s' % (get_answer_part(d['question']))
+    s += '</div>'
+    session['articleID'] = d['article_id']
+    return s
+
 
 def appears_in_test(word, d):
-    '''
-    如果字符串里没有指定的单词，则返回逗号加单词
-    :param word: 指定单词
-    :param d: 字符串
-    :return: 逗号加单词
-    '''
     if not word in d:
         return ''
     else:
         return ','.join(d[word])
 
 
+def get_time():
+    return datetime.now().strftime('%Y%m%d%H%M') # upper to minutes
+
+
+def get_question_part(s):
+    s = s.strip()
+    result = []
+    flag = 0
+    for line in s.split('\n'):
+        line = line.strip()
+        if line == 'QUESTION':
+            result.append(line)
+            flag = 1
+        elif line == 'ANSWER':
+            flag = 0
+        elif flag == 1:
+            result.append(line)
+    return '\n'.join(result)
+
+
+def get_answer_part(s):
+    s = s.strip()
+    result = []
+    flag = 0
+    for line in s.split('\n'):
+        line = line.strip()
+        if line == 'ANSWER':
+            flag = 1
+        elif flag == 1:
+            result.append(line)
+    # https://css-tricks.com/snippets/javascript/showhide-element/
+    js = '''
+<script type="text/javascript">
+
+    function toggle_visibility(id) {
+       var e = document.getElementById(id);
+       if(e.style.display == 'block')
+          e.style.display = 'none';
+       else
+          e.style.display = 'block';
+    }
+</script>   
+    '''
+    html_code = js
+    html_code += '\n'
+    html_code += '<button onclick="toggle_visibility(\'answer\');">ANSWER</button>\n'
+    html_code += '<div id="answer" style="display:none;">%s</div>\n' % ('\n'.join(result))
+    return html_code
+
+
+def get_flashed_messages_if_any():
+    messages = get_flashed_messages()
+    s = ''
+    for message in messages:
+        s += '<div class="alert alert-warning" role="alert">'
+        s += f'Congratulations! {message}'
+        s += '</div>'
+    return s
+
+
+@app.route("/<username>/reset", methods=['GET', 'POST'])
+def user_reset(username):
+    if request.method == 'GET':
+        session['articleID'] = None
+        return redirect(url_for('userpage', username=username))
+    else:
+        return 'Under construction'
+
+
 @app.route("/mark", methods=['GET', 'POST'])
 def mark_word():
-    '''
-    标记单词
-    :return: 重定位到主界面
-    '''
     if request.method == 'POST':
         d = load_freq_history(path_prefix + 'static/frequency/frequency.p')
         lst_history = pickle_idea.dict2lst(d)
@@ -70,45 +223,318 @@ def mark_word():
         d = pickle_idea.merge_frequency(lst, lst_history)
         pickle_idea.save_frequency_to_pickle(d, path_prefix + 'static/frequency/frequency.p')
         return redirect(url_for('mainpage'))
-    else: # 不回应GET请求
+    else:
         return 'Under construction'
 
 
+
 @app.route("/", methods=['GET', 'POST'])
 def mainpage():
-    '''
-    根据GET或POST方法来返回不同的主界面
-    :return: 主界面
-    '''
     if request.method == 'POST':  # when we submit a form
         content = request.form['content']
         f = WordFreq(content)
         lst = f.get_freq()
-        # save history
+        page = '<form method="post" action="/mark">\n'
+        count = 1
+        for x in lst:
+            page += '<p><font color="grey">%d</font>: <a href="%s">%s</a> (%d)  <input type="checkbox" name="marked" value="%s"></p>\n' % (count, youdao_link(x[0]), x[0], x[1], x[0])
+            count += 1
+        page += ' <input type="submit" value="确定并返回"/>\n'
+        page += '</form>\n'
+        # save history 
         d = load_freq_history(path_prefix + 'static/frequency/frequency.p')
         lst_history = pickle_idea.dict2lst(d)
         d = pickle_idea.merge_frequency(lst, lst_history)
         pickle_idea.save_frequency_to_pickle(d, path_prefix + 'static/frequency/frequency.p')
-        return render_template('mainpage_post.html', lst=lst, yml=Yaml.yml)
+        
+        return page
+    elif request.method == 'GET': # when we load a html page
+        page = '''
+             <html lang="zh">
+               <head>
+               <meta charset="utf-8">
+               <meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=0.5, maximum-scale=3.0, user-scalable=yes" />
+               <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-EVSTQN3/azprG1Anm3QDgpJLIm9Nao0Yz1ztcQTwFspd3yD65VohhpuuCOmLASjC" crossorigin="anonymous">
 
-    elif request.method == 'GET':  # when we load a html page
-        random_ads = get_random_ads()
-        number_of_essays = total_number_of_essays()
+                 <title>EnglishPal 英文单词高效记</title>
+
+               </head>
+               <body>
+        '''
+        page += '<div class="container-fluid">'
+        page += '<p><b><font size="+3" color="red">English Pal - Learn English smartly!</font></b></p>'
+        if session.get('logged_in'):
+            page += ' <a href="%s">%s</a></p>\n' % (session['username'], session['username'])
+        else:
+            page += '<p><a href="/login">登录</a>  <a href="/signup">成为会员</a> <a href="/static/usr/instructions.html">使用说明</a></p>\n'
+        #page += '<p><img src="%s" width="400px" alt="advertisement"/></p>' % (get_random_image(path_prefix + 'static/img/'))
+        page += '<p><b>%s</b></p>' % (get_random_ads())
+        page += '<div class="alert alert-success" role="alert">共有文章 <span class="badge bg-success"> %d </span> 篇</div>' % (total_number_of_essays())
+        page += '<p>粘帖1篇文章 (English only)</p>'
+        page += '<form method="post" action="/">'
+        page += ' <textarea name="content" rows="10" cols="120"></textarea><br/>'
+        page += ' <input type="submit" value="get文章中的词频"/>'
+        page += ' <input type="reset" value="清除"/>'
+        page += '</form>'
         d = load_freq_history(path_prefix + 'static/frequency/frequency.p')
-        d_len = len(d)
-        lst = sort_in_descending_order(pickle_idea.dict2lst(d))
-        return render_template('mainpage_get.html', random_ads=random_ads, number_of_essays=number_of_essays,
-                               d_len=d_len, lst=lst, yml=Yaml.yml)
+        if len(d) > 0:
+            page += '<p><b>最常见的词</b></p>'
+            for x in sort_in_descending_order(pickle_idea.dict2lst(d)):
+                if x[1] <= 99:
+                    break
+                page += '<a href="%s">%s</a> %d\n' % (youdao_link(x[0]), x[0], x[1])
 
+        page += ' <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js" integrity="sha384-MrcW6ZMFYlzcLA8Nl+NtUVF0sA7MsXsP1UyJoMp4YLEuNSfAP+JcXn/tWtIaxVXM" crossorigin="anonymous"></script>'
+        page += '</div>'
+        page += '</body></html>'
+        return page
+
+
+@app.route("/<username>/mark", methods=['GET', 'POST'])
+def user_mark_word(username):
+    username = session[username]
+    user_freq_record = path_prefix + 'static/frequency/' +  'frequency_%s.pickle' % (username)
+    if request.method == 'POST':
+        d = load_freq_history(user_freq_record)
+        lst_history = pickle_idea2.dict2lst(d)
+        lst = []
+        for word in request.form.getlist('marked'):
+            lst.append((word, [get_time()]))
+        d = pickle_idea2.merge_frequency(lst, lst_history)
+        pickle_idea2.save_frequency_to_pickle(d, user_freq_record)
+        return redirect(url_for('userpage', username=username))
+    else:
+        return 'Under construction'
+
+
+@app.route("/<username>/<word>/unfamiliar", methods=['GET', 'POST'])
+def unfamiliar(username,word):
+    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
+    pickle_idea.unfamiliar(user_freq_record,word)
+    session['thisWord'] = word  # 1. put a word into session
+    session['time'] = 1
+    return redirect(url_for('userpage', username=username))
+
+@app.route("/<username>/<word>/familiar", methods=['GET', 'POST'])
+def familiar(username,word):
+    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
+    pickle_idea.familiar(user_freq_record,word)
+    session['thisWord'] = word  # 1. put a word into session
+    session['time'] = 1
+    return redirect(url_for('userpage', username=username))
+
+@app.route("/<username>/<word>/del", methods=['GET', 'POST'])
+def deleteword(username,word):
+    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
+    pickle_idea2.deleteRecord(user_freq_record,word)
+    flash(f'<strong>{word}</strong> is no longer in your word list.')
+    return redirect(url_for('userpage', username=username))
+
+@app.route("/<username>", methods=['GET', 'POST'])
+def userpage(username):
+    
+    if not session.get('logged_in'):
+        return '<p>请先<a href="/login">登录</a>。</p>'
+
+    user_expiry_date = session.get('expiry_date')
+    if datetime.now().strftime('%Y%m%d') > user_expiry_date:
+        return '<p>账号 %s 过期。</p><p>为了提高服务质量，English Pal 收取会员费用， 每天0元。</p> <p>请决定你要试用的时间长度，扫描下面支付宝二维码支付。 支付时请注明<i>English Pal Membership Fee</i>。 我们会于12小时内激活账号。</p><p><img src="static/donate-the-author-hidden.jpg" width="120px" alt="支付宝二维码" /></p><p>如果有问题，请加开发者微信 torontohui。</p> <p><a href="/logout">登出</a></p>' % (username)
+
+    
+    username = session.get('username')
+
+    user_freq_record = path_prefix + 'static/frequency/' +  'frequency_%s.pickle' % (username)
+    
+    if request.method == 'POST':  # when we submit a form
+        content = request.form['content']
+        f = WordFreq(content)
+        lst = f.get_freq()
+        page = '<meta charset="UTF8">'        
+        page += '<meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=0.5, maximum-scale=3.0, user-scalable=yes" />'        
+        page += '<p>勾选不认识的单词</p>'
+        page += '<form method="post" action="/%s/mark">\n' % (username)
+        page += ' <input type="submit" name="add-btn" value="加入我的生词簿"/>\n'        
+        count = 1
+        words_tests_dict = pickle_idea.load_record(path_prefix + 'static/words_and_tests.p')        
+        for x in lst:
+            page += '<p><font color="grey">%d</font>: <a href="%s" title="%s">%s</a> (%d)  <input type="checkbox" name="marked" value="%s"></p>\n' % (count, youdao_link(x[0]), appears_in_test(x[0], words_tests_dict), x[0], x[1], x[0])
+            count += 1
+        page += '</form>\n'
+        return page
+    
+    elif request.method == 'GET': # when we load a html page
+        page = '<meta charset="UTF8">\n'
+        page += '<meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=0.5, maximum-scale=3.0, user-scalable=yes" />\n'
+        page += '<meta name="format-detection" content="telephone=no" />\n' # forbid treating numbers as cell numbers in smart phones
+        page += '<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-EVSTQN3/azprG1Anm3QDgpJLIm9Nao0Yz1ztcQTwFspd3yD65VohhpuuCOmLASjC" crossorigin="anonymous">'
+        page += '<title>EnglishPal Study Room for %s</title>' % (username)
+        page += '<div class="container-fluid">'
+        page += '<p><b>English Pal for <font color="red">%s</font></b> <a class="btn btn-secondary" href="/logout" role="button">登出</a></p>' % (username)
+        page += get_flashed_messages_if_any()
+        page += '<p><b>阅读文章并回答问题</b></p>\n'
+        page += '<p><a class="btn btn-success" href="/%s/reset" role="button"> 下一篇 Next Article </a></p>' % (username)
+        page += '<div id="text-content">%s</div>'  % (get_today_article(user_freq_record, session['articleID']))
+        page += '<p><b>收集生词吧</b> （可以在正文中划词，也可以复制黏贴）</p>'
+        page += '<form method="post" action="/%s">' % (username)
+        page += ' <textarea name="content" id="selected-words" rows="10" cols="120"></textarea><br/>'
+        page += ' <input type="submit" value="get 所有词的频率"/>'
+        page += ' <input type="reset" value="清除"/>'
+        page += '</form>\n'
+        page += ''' 
+                 <script>
+                   function getWord(){ 
+                       var word = window.getSelection?window.getSelection():document.selection.createRange().text;
+                       return word;
+                   }
+                   function fillinWord(){
+                       var element = document.getElementById("selected-words");
+                       element.value = element.value + " " + getWord();
+                   }
+                   document.getElementById("text-content").addEventListener("click", fillinWord, false);
+                   document.getElementById("text-content").addEventListener("touchstart", fillinWord, false);
+                 </script>
+                 '''
+        if session.get('thisWord'):
+            page += '''
+                   <script type="text/javascript">
+                        //point to the anchor in the page whose id is aaa if it exists
+                        window.onload = function(){
+                            var element = document.getElementsByName("aaa");
+                            if (element != null)
+                                document.getElementsByName("aaa")[0].scrollIntoView(true);
+                        }
+                   </script> 
+                   '''
+
+        d = load_freq_history(user_freq_record)
+        if len(d) > 0:
+            page += '<p><b>我的生词簿</b></p>'
+            lst = pickle_idea2.dict2lst(d)
+            lst2 = []
+            for t in lst:
+                lst2.append((t[0], len(t[1])))
+            for x in sort_in_descending_order(lst2):
+                word = x[0]
+                freq = x[1]
+                if session.get('thisWord') == x[0] and session.get('time') == 1:
+                    page += '<a name="aaa"></a>'    # 3. anchor
+                    session['time'] = 0   # discard anchor
+                if isinstance(d[word], list): # d[word] is a list of dates
+                    if freq > 1:
+                        page += '<p class="new-word"> <a class="btn btn-light" href="%s" role="button">%s</a>(<a title="%s">%d</a>) <a class="btn btn-success" href="%s/%s/familiar" role="button">熟悉</a> <a class="btn btn-warning" href="%s/%s/unfamiliar" role="button">不熟悉</a>  <a class="btn btn-danger" href="%s/%s/del" role="button">删除</a> </p>\n' % (youdao_link(word), word, '; '.join(d[word]), freq,username, word,username,word, username,word)
+                    else:
+                        page += '<p class="new-word"> <a class="btn btn-light" href="%s" role="button">%s</a>(<a title="%s">%d</a>) <a class="btn btn-success" href="%s/%s/familiar" role="button">熟悉</a> <a class="btn btn-warning" href="%s/%s/unfamiliar" role="button">不熟悉</a>  <a class="btn btn-danger" href="%s/%s/del" role="button">删除</a> </p>\n' % (youdao_link(word), word, '; '.join(d[word]), freq,username, word,username,word, username,word)
+                elif isinstance(d[word], int): # d[word] is a frequency. to migrate from old format.
+                    page += '<a href="%s">%s</a>%d\n' % (youdao_link(word), word, freq)
+        page += '<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js" integrity="sha384-MrcW6ZMFYlzcLA8Nl+NtUVF0sA7MsXsP1UyJoMp4YLEuNSfAP+JcXn/tWtIaxVXM" crossorigin="anonymous"></script>'
+        page += '</div>'
+        return page
+
+### Sign-up, login, logout ###
+@app.route("/signup", methods=['GET', 'POST'])
+def signup():
+    if request.method == 'GET':
+        return render_template('signup.html')
+    elif request.method == 'POST':
+        username = request.form['username']
+        password = request.form['password']
+
+
+
+
+def check_number_exist(password_str):
+    """
+    判断密码是否含有数字
+
+    """
+    for c in password_str:
+        if c.isnumeric():
+            return True
+    return False
+
+def check_letter_exist(password_str):
+    """
+    判断密码是否含有字母
+
+    """
+    for c in password_str:
+        if c.isalpha():
+            return True
+    return False
+#规则1：密码长度大于8
+    if len(password) >= 8:
+        strength_level += 1
+    else:
+        print('密码强度要求至少8位')
+
+    #规则2：密码必须包含数字
+    if check_number_exist(password):
+        strength_level += 1
+    else:
+        print('密码要求包含数字')
+
+    #规则3：密码必须包含字母
+    if check_letter_exist(password):
+        strength_level += 1
+    else:
+        print('密码要求包含字母')
+
+
+
+        available = check_username_availability(username)
+        if not available:
+            flash('用户名 %s 已经被注册。' % (username))
+            return render_template('signup.html')
+        elif len(password.strip()) < 4:
+            return '密码过于简单。'
+        else:
+            add_user(username, password)
+            verified = verify_user(username, password)
+            if verified:
+                session['logged_in'] = True
+                session[username] = username
+                session['username'] = username
+                session['expiry_date'] = get_expiry_date(username)
+                session['articleID'] = None
+                return '<p>恭喜，你已成功注册， 你的用户名是 <a href="%s">%s</a>。</p>\
+                <p><a href="/%s">开始使用</a> <a href="/">返回首页</a><p/>' % (username, username, username)
+            else:
+                return '用户名密码验证失败。'
+
+
+@app.route("/login", methods=['GET', 'POST'])
+def login():
+    if request.method == 'GET':
+        if not session.get('logged_in'):
+            return render_template('login.html')
+        else:
+            return '你已登录 <a href="/%s">%s</a>。 登出点击<a href="/logout">这里</a>。' % (session['username'], session['username'])
+    elif request.method == 'POST':
+        # check database and verify user
+        username = request.form['username']
+        password = request.form['password']
+        verified = verify_user(username, password)
+        if verified:
+            session['logged_in'] = True
+            session[username] = username
+            session['username'] = username
+            user_expiry_date = get_expiry_date(username)
+            session['expiry_date'] = user_expiry_date
+            session['articleID'] = None
+            return redirect(url_for('userpage', username=username))
+        else:
+            return '无法通过验证。'
+
+
+@app.route("/logout", methods=['GET', 'POST'])
+def logout():
+    session['logged_in'] = False
+    return redirect(url_for('mainpage'))
 
 
 if __name__ == '__main__':
-    '''
-    运行程序
-    '''
-    # app.secret_key = os.urandom(16)
-    # app.run(debug=False, port='6000')
-    app.run(debug=True)
-    # app.run(debug=True, port='6000')
-    # app.run(host='0.0.0.0', debug=True, port='6000')
-    # print(mod5('123'))
+    #app.secret_key = os.urandom(16)
+    #app.run(debug=False, port='6000')
+    app.run(debug=True)        
+    #app.run(debug=True, port='6000')
+    #app.run(host='0.0.0.0', debug=True, port='6000')