#include "bits/stdc++.h"
using namespace std;
#define MAX 31
int main() {
	int V0, V1, V2, V3;
	cin >> V0 >> V1 >> V2 >> V3;
	int ans = 999;
	for (int A = 1; A < MAX; A++)
	{
		for (int B = A + 1; B < MAX; B++)
		{
			for (int C = B + 1; C < MAX; C++)
			{
				vector<int> dp(MAX, 999);
				dp[0] = 0;
				for (int i = 0; i < MAX - A; i++)
				{
					dp[i + A] = min(dp[i + A], dp[i] + 1);
				}
				for (int i = 0; i < MAX - B; i++)
				{
					dp[i + B] = min(dp[i + B], dp[i] + 1);
				}
				for (int i = 0; i < MAX - C; i++)
				{
					dp[i + C] = min(dp[i + C], dp[i] + 1);
				}
				ans = min(ans, dp[V0] + dp[V1] + dp[V2] + dp[V3]);
			}
		}
	}
	cout << ans << endl;
}