#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < n; ++i)

int main(void) {
	int v1, v2, v3, v4;
	cin >> v1 >> v2 >> v3 >> v4;
	
	int ans = 1e9;
	for(int A = 1; A <= 30; ++A) {
		for(int B = A + 1; B <= 30; ++B) {
			for(int C = B + 1; C <= 30; ++C) {
				vector<int> dp(31, 1e6);
				dp[0] = 0;
				for(int i = 0; i <= 30; ++i) {
					if(i + A <= 30) dp[i + A] = min(dp[i + A], dp[i] + 1);
					if(i + B <= 30) dp[i + B] = min(dp[i + B], dp[i] + 1);
					if(i + C <= 30) dp[i + C] = min(dp[i + C], dp[i] + 1);
				}
				
				ans = min(ans, dp[v1] + dp[v2] + dp[v3] + dp[v4]);
			}
		}
	}
	
	cout << ans << endl;
}