var jumin = input;

function input() {
    var input = document.getElementById("jumin").value;
    jumin = input;
}

function output() {
    jumin = document.getElementById("jumin").value;

    var _cent;
    var _year = jumin[0] + jumin[1];
    var _month = jumin[2] + jumin[3];
    var _day = jumin[4] + jumin[5];

    if (_year <= 20) {
        _cent = 20;
    } else {
        _cent = 19;
    }

    var date = new Date();
    var curYear = date.getFullYear();
    var birthYear = _cent + _year;
    var age = curYear - birthYear;

    document.getElementById("demo").innerHTML = "생일:" + _cent + _year + "년 " + _month + "월 " + _day + "일" + "<br>" + "나이 " +age;
}