import java.util.Arrays;
import java.util.Scanner;

public class Yukicoder27 {

	static int[][] pat = {{0, 1, 2, 3}, {0, 1, 3, 2}, {0, 2, 3, 1}, {1, 2, 3, 0}};

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int[] V = new int[4];
		for (int i = 0; i < 4; i++) V[i] = sc.nextInt();
		Arrays.sort(V);

		int[] board = new int[3];
		int min = Integer.MAX_VALUE;

		for (int i = 0; i < 4; i++) {
			board[0] = V[pat[i][0]];
			board[1] = V[pat[i][1]];
			board[2] = V[pat[i][2]];
			
			for (int j = 0; j < 30; j++) {
				for (int k = 0; k < 30; k++) {
					for (int l = 0; l < 30; l++) {
						if (board[0] * j + board[1] * k + board[2] * l == V[pat[i][3]]) min = Math.min(min, j+k+l);
					}
				}
			}
		}
		System.out.println(min + 3);
	}

}