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


public class Main_yukicoder27 {

    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 max = v[3];

        int min = Integer.MAX_VALUE;
        for (int i = 1; i < max; i++) {
            for (int j = i + 1; j < max; j++) {
            	next:
                for (int k = j + 1; k <= max; k++) {
                	int sum = 0;
                	for (int e : v) {
                		int tmp = isOK(e, i, j, k);
                		if (tmp == 0) {
                			continue next;
                		}
                		sum += tmp;
                	}
                	min = Math.min(min, sum);
                }
            }
        }

        System.out.println(min);

        sc.close();
    }

	private static int isOK(int v, int a, int b, int c) {
		int min = Integer.MAX_VALUE;
		for (int i = v / c; i >= 0; i--) {
			for (int j = (v - c * i) / b; j >= 0; j--) {
				if ((v - c * i - b * j) % a == 0) {
					min = Math.min(min, i + j + (v - c * i - b * j) / a);
				}
			}
		}

		if (min == Integer.MAX_VALUE) {
			return 0;
		} else {
			return min;
		}
	}
}