function quiz() {
        var count = 3;
        var tmID;
        var infobox = document.getElementById("info");
        var start = document.getElementById("start");
        var clear = document.getElementById("clear");
     
        function quiz() {
          if (--count < 0) {
            infobox.innerHTML = "終了";
          } else {
            infobox.innerHTML = count + "秒前";
            tmID = setTimeout(quiz, 1000);
          }
        }
     
    function startquiz() {
      tmID = setTimeout(quiz, 1000);
      var list = document.getElementsByTagName('div');
      for (let i of list){
        i.removeEventListener("click", startquiz, false);
        clear.addEventListener('click', stopquiz);
      }
    }
     
    function stopquiz() {
      if (count >= 0) {
        clearTimeout(tmID);
        infobox.innerHTML = "成功";
      }
    }
     
    start.addEventListener("click", startquiz, false);
    };
    document.addEventListener("DOMContentLoaded", quiz, false);