// 1. cycle
function nod (a,b) {

	var first = a;
	var second = b;
	var reminder;

	while (second != 0) {
		reminder = first % second;
		first = second;
		second = reminder;
	}

	return first;
}


// 2. recursion
function nod (first, second) {
	if(second == 0) {
		return first;
	} else {
		return nod(second, first % second);
	}
}