function main() {
    var count = 6,
    tmID,
    button = document.getElementById("start"), 
    atari = document.getElementById("box"),
    finish = document.getElementById("info");
    function CountDown(){
        if (--count == 0) {
            finish.innerHTML = "終了";
            atari.removeEventListener("click", stopCountDown, false);
        } else {
            finish.innerHTML = count + "秒前";
            tmID = setTimeout(CountDown, 1000);/*1000ms=1秒*/ 
        }
    }

    function stopCountDown() {
        if (count >= 0) {
            clearTimeout(tmID);
            button.innerHTML = "爆発阻止成功です！";
        }
        finish.innerHTML = "終了";
        atari.innerHTML = "みっけ！";
        atari.removeEventListener("click", stopCountDown, false);
    }

    function startCountDown() {
        tmID = setTimeout(CountDown, 1000);/*1000ms=1秒*/ 
        button.removeEventListener("click", startCountDown, false);
        atari.addEventListener("click", stopCountDown, false);
    }
    button.addEventListener("click", startCountDown, false);
};
document.addEventListener("DOMContentLoaded", main, false);