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


public class Main_yukicoder27_1 {

    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();
        }

        int max = 30;

        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) {
		final int INF = Integer.MAX_VALUE / 2;
		int[] dp = new int[v + 1];
		Arrays.fill(dp, INF);
		dp[0] = 0;

		for (int i = 0; i < v; i++) {
			if (dp[i] == INF) {
				continue;
			}

			if (i + a <= v) {
				dp[i + a] = Math.min(dp[i + a], dp[i] + 1);
			}
			if (i + b <= v) {
				dp[i + b] = Math.min(dp[i + b], dp[i] + 1);
			}
			if (i + c <= v) {
				dp[i + c] = Math.min(dp[i + c], dp[i] + 1);
			}
		}

		if (dp[v] == INF) {
			return 0;
		} else {
			return dp[v];
		}
	}
}