function CountDown() {
    var count = 4, 
        tmID,
        infobox = document.getElementById("info"),
        hit = document.getElementById("hit"),
        finish = document.getElementById("finish");
        
    function CountDown() {
        if (--count < 0) {
            finish.innerHTML = "終了";
        } else {
            finish.innerHTML = count + "秒前";
            tmID = setTimeout(CountDown, 1000);
        }
    }
    function startCountDown() {
        tmID = setTimeout(CountDown, 1000);
        infobox.removeEventListener("click", startCountDown, false);
        hit.addEventListener("click", stopCountDown, false);
    }
    function stopCountDown() {
        if (count >= 0) {
            clearTimeout(tmID);
            infobox.innerHTML = "当たり！";
        }

	hit.removeEventListener("click", stopCountDown, false);
    }
    infobox.addEventListener("click", startCountDown, false);  
}
document.addEventListener("DOMContentLoaded", CountDown, false);