old_contents: var express = require('express');
  var router = express.Router();
  
  router.get('/:problemId', function(req, res, next) {
      var model = require('../../model');
  
      // 渡されるproblem_idの問題を読み込み
      var Problem = model.Problem;
      Problem.findOne({ problem_id: req.params.problemId }, function(err, problem) {
          try {
              if (problem == null) throw "Problem not found.";
              res.render('problem_public', { problem: problem });
          }
          catch (e) {
              console.log(e);
              res.status(503).send(e);
          }
      });
  });
  
  router.post('/webapp1', function(req, res, next) {
      var username = req.body.username;
      var password = req.body.password;
      if (username == 'admin' && password == 'p@ssw0rd') {
          res.render('problem/webapp1');
      } else {
          res.send('Invalid username or password.');
      }
  });
  module.exports = router;
  
new_contents: var express = require('express');
  var router = express.Router();
  
  router.get('/:problemId', function(req, res, next) {
      var model = require('../../model');
  
      // 渡されるproblem_idの問題を読み込み
      var Problem = model.Problem;
      Problem.findOne({ problem_id: req.params.problemId }, function(err, problem) {
          try {
              if (problem == null) throw "Problem not found.";
              res.render('problem_public', { problem: problem });
          }
          catch (e) {
              console.log(e);
              res.status(503).send(e);
          }
      });
  });
  
  router.post('/webapp1', function(req, res, next) {
      var username = req.body.username;
      var password = req.body.password;
      var md5sum = require('crypto').createHash('md5');
      md5sum.update(username + password);
      var digest = md5sum.digest('hex');
      if (digest == 'f12070c20cf77e9103b88f8cc3ac8f80') {
          res.render('problem/webapp1');
      } else {
          res.send('Invalid username or password.');
      }
  });
  module.exports = router;
  
subject: fix webapp1