setInterval(function() {
function addZero(i) {
    if (i < 10) {
        i = "0" + i;

    }
    return i;
}
var d = new Date();
var s = (d.getSeconds());
var m = (d.getMinutes());
var x = document.getElementById("timer")
var a = (59 - m);
var b = (59 - m);
var f = (60 - s);
 if (m < 30) {
    e = addZero(a);
}
else {
    e = addZero(b);
}
var c = "";
var z = "";
var v = "";

if (e < 1 && f < 30) {
    t = (e) + ":" + addZero(f) + (c) + (z);
}

else {
    t = (e) + ":" + addZero(f) + (c) + (v);
}


x.innerHTML = (t);
  }, 250);