// yukicoder: No.27 板の準備
// 2019.5.26 bal4u

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int gcd(int a, int b)
{
	int r;
	while (b != 0) r = a % b, a = b, b = r;
	return a;
}

int v[4];
int cmp(const void *a, const void *b) { return *(int *)a - *(int *)b; }

short a[100];
void dp(int A, int B, int C) {
	int i, j, k;
	memset(a, -1, sizeof(short)*(v[3]+1));
	a[0] = 0;
	for (i = 1; i*A <= v[3]; i++) a[i*A] = i;
	for (i = v[3]; i >= 0; i--) if (a[i] >= 0) {
		for (j = 1; (k=i+j*B) <= v[3]; j++) {
			if (a[k] < 0 || a[k] > a[i]+j) a[k] = a[i]+j;
		}
	}
	for (i = v[3]; i >= 0; i--) if (a[i] >= 0) {
		for (j = 1; (k=i+j*C) <= v[3]; j++) {
			if (a[k] < 0 || a[k] > a[i]+j) a[k] = a[i]+j;
		}
	}
}
	
int main()
{
	int i, j, k, f, A, B, C, ans;
	
	for (i = 0; i < 4; i++) scanf("%d", v+i);
	qsort(v, 4, sizeof(int), cmp);
	f = 0; for (i = 1; i < 4; i++) {
		if (v[i] == v[i-1]) { puts("4"); return 0; }
		if (v[i] == 2*v[i-1]) f = 1;
	}
	if (f) { puts("5"); return 0; }
	for (i = 1; i < 4; i++) for (j = 0; j < i; j++) {
		for (k = 0; k <= j; k++) {
			if (v[i]-v[j] == v[k]) { puts("5"); return 0; }
		}
	}
	A = v[0], ans = 1000;
	for (B = 1; B < v[3]; B++) if (B != A) {
		for (C = B+1; C <= v[3]; C++) if (C != A) {
			dp(A, B, C);
			if (a[v[1]] > 0 && a[v[2]] > 0 && a[v[3]] > 0) {
				k = 1 + a[v[1]] + a[v[2]] + a[v[3]];
				if (k < ans) ans = k;
			}
		}
	}
	printf("%d\n", ans);
	return 0;
}