fn main
[
	var lines := list_break_to_lines(read_lazy(h[0]));
	var list1 := empty(int);
	var map2 := infinite(0);
	for l in lines do [
		var b := list_break_whitespace(l);
		list1 +<= ston(b[0]);
		map2[ston(b[1])] += 1;
	]
	var dist := 0;
	for i := 0 to len(list1) do
		dist += list1[i] * map2[list1[i]];
	write(h[1], ntos(dist) + nl);
]