FMars

var counter = document.getElementById("counter")
var hiddenText = document.getElementById("hidden-text")
var run = function(seconds) {
  var interval = setInterval(function(){
    if (seconds > 0) {
      counter.textContent = seconds--;
    }
    else 
    {
      hiddenText.style.display = "block";
      counter.style.display = "none";
      clearInterval(interval);
    }
  }, 1000)
}