fn main
[
	var lines := list_break_to_lines(read_lazy(h[0]));
	var sections := list_break(lines, "");
	var ranges := empty(tuple3(int, int, int));
	for l in sections[0] do [
		var ll := list_break(l, '-');
		var a := ston(ll[0]);
		var b := ston(ll[1]);
		ranges +<= mktuple3(b - a, a, b);
	]
	ranges := list_sort(ranges);
	ranges := list_reverse(ranges);
	var fresh := 0;
	for i := 0 to len(ranges) do [
		var a := ranges[i].v2;
		var b := ranges[i].v3;
		for j := 0 to i do [
			var aa := ranges[j].v2;
			var bb := ranges[j].v3;
			if aa <= a then
				a := max(a, bb + 1);
			if bb >= b then
				b := min(b, aa - 1);
			if b < a then
				goto skip_this;
				
		]
		fresh += b - a + 1;
skip_this:
	]
	write(h[1], ntos(fresh) + nl);
]