function add_thousands_separator(input) {
	var s = input.toString(), l = s.length, o = '';
	while (l > 3) {
		var c = s.substr(l - 3, 3);
		o = ',' + c + o;
		s = s.replace(c, '');
		l -= 3;
	}
	o = s + o;
	return o;
}