<script type="text/javascript">

var first = function(n)
{
  if(n < 1 || isNaN(n)) return;
  var i = 0;
  while((i + 1) * 3 < n) i++;
  return i;
},

second = function(a)
{
  if(!(a instanceof Array)) return;
  var l = a.length, i = 0;
  while(l--) i += a[l];
  return parseInt(i / a.length);
};

alert(first(15));
alert(second([5,1,2,4,1,2,4,1,3,4,5,2,4,5]));

</script>