#include <iostream>
#include <cstring>
using namespace std;
#define REP(i, n)           for(int(i)=0;(i)<(n);++(i))

const int MAXV = 30;

int main(){
    int V0,V1,V2,V3;
    cin >> V0 >> V1 >> V2 >> V3;
    int minv = 10000;

    for(int A = 1; A <= MAXV; A++){
        for(int B = A+1; B <= MAXV; B++){
            for(int C = B+1; C <= MAXV; C++){
                int dp[MAXV+1];
                for(int i = 0; i <= MAXV; i++) dp[i] = 10000;
                dp[0] = 0;
                int k[3];
                k[0] = A, k[1] = B, k[2] = C;
                for(int i = 0; i < 3; i++){
                    for(int j = 0; j <= MAXV; j++){
                        if(j+k[i] <= MAXV){
                            dp[j+k[i]] = min(dp[j+k[i]], dp[j]+1);
                        }
                    }
                }
                minv = min(minv, dp[V0]+dp[V1]+dp[V2]+dp[V3]);
            }
        }
    }
    cout << minv << endl;
    return 0;
}