module main;

import std;

void main()
{
	// 入力
	int d = readln.chomp.to!int;
	int H1 = readln.chomp.to!int;
	int H2 = readln.chomp.to!int;
	int H3 = readln.chomp.to!int;
	// 答えの計算と出力
	if (H2 == 0 && (H1 == 0 || H3 == 0)) {
		writeln(-1);
		return;
	}
	// H2を一番高くする場合
	int ans1 = 0, h1 = H1, h2 = H2, h3 = H3;
	while (h1 >= h2) {
		h1 = max(0, h1 - d);
		ans1++;
	}
	while (h3 >= h2) {
		h3 = max(0, h3 - d);
		ans1++;
	}
	// H2を一番低くする場合
	int ans2 = 0;
	h1 = H1, h2 = H2, h3 = H3;
	while (h1 <= h2) {
		h2 = max(0, h2 - d);
		ans2++;
	}
	while (H3 <= H2) {
		h2 = max(0, h2 - d);
		ans2++;
	}
	writeln(min(ans1, ans2));
}