complete game within 20 sec

game limit is 1 min but if user will complete game within 20 sec then he will get 500 bonus points

how to code for this

//this is count up timer script

var intID;

var endTime = getTimer()+(59*1000);

makeTime();

function updateTimer() {

  var t = endTime-getTimer();

  if (t>0) {

  makeTime();

  showTime(t);

  } else {

  stopTimer();

  showTime(0);

  gotoAndStop("over");

  trace("lost");

  }

}

function makeTime() {

clearInterval(intID);

intID = setInterval(updateTimer, 100);

}

function stopTimer() {

  clearInterval(intID);

}

function showTime(t) {

  dispTime.text = (t/1000) >> 0;

}