#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <cstdio>
#include <set>
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
const int INF = 1e6;
int dp[40];

int main(void){
	int v[4];
	int ans = INF;
	rep(i, 4) cin >> v[i];
	for (int i = 1; i <= 30; ++i){
		for (int j = i + 1; j <= 30; ++j){
			for (int k = j + 1; k <= 30; ++k){
				rep(l, 31) dp[l] = INF;
				dp[0] = 0;
				dp[i] = dp[j] = dp[k] = 1;
				int memo[] = {i, j, k};
				for (int len = 0; len <= 30; ++len){
					if(dp[len] == INF) continue;
					for (int t = 0; t < 3; ++t){
						//kubaru
						if(len + memo[t] <= 30){
							dp[len + memo[t]] = min(dp[len + memo[t]], dp[len] + 1);
							// printf("%d\n", dp[len + memo[t]]);
						}
					}
				}

				int tmp = 0;
				rep(l, 4){
					// printf("%d\n",dp[v[l]]);
					tmp += dp[v[l]];
				}
				ans = min(ans, tmp);
			}
		}
	}
	printf("%d\n", ans);
	return 0;
}