text: var num = Math.floor(Math.random() * 99) + 1;
  var count = 0;
  var guessnum;
  var max = 99;
  var min = 1;
  
  function setSmoke() {
      count++;
      switch (count) {
          case 1:
              document.img1.src = "img/smoke.png";
              break;
          case 2:
              document.img2.src = "img/smoke.png";
              break;
          case 3:
              document.img3.src = "img/smoke.png";
              break;
          case 4:
              document.img4.src = "img/smoke.png";
              break;
          case 5:
              document.img5.src = "img/smoke.png";
              break;
          case 6:
              document.img6.src = "img/smoke.png";
              break;
      }
  }
  
  function Guess() {
      guessnum = document.getElementById("number").value;
      if (guessnum == num) {
          alert('you get it , guess ' + count + ' times');
      } else if (count < 6) {
          setSmoke();
          if (guessnum > min && guessnum < num) {
              min = guessnum;
          } else if (guessnum < max && guessnum > num) {
              max = guessnum;
          }
          alert('wrong ,' + min + '~' + max);
      } else {
          alert('game over');
      }
  }
  
  function restart() {
      alert('restart');
      document.img1.src = "img/bomber.png";
      document.img2.src = "img/bomber.png";
      document.img3.src = "img/bomber.png";
      document.img4.src = "img/bomber.png";
      document.img5.src = "img/bomber.png";
      document.img6.src = "img/bomber.png";
      num = Math.floor(Math.random() * 99) + 1;
      max = 99;
      min = 1;
      count = 0;
  }
  