#define _USE_MATH_DEFINES
 
#include <iostream>
#include <iomanip>
 
#include <algorithm>
#include <cmath>
 
#include <string>
//#include <array>
#include <list>
#include <queue>
#include <vector>
#include <complex>
#include <set>
#include <map>
 
/////////
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i,n) REP(i,0,n)
#define P(p) cout<<(p)<<endl;
 
#define PII pair<int,int>
/////////
typedef long long LL;
typedef long double LD;
/////////
using namespace::std;
/////////

int solve(int V,int A,int B,int C){
	int ans = -1;

	if(V < A){
		return -1;
	}
	for(int a=0;a<=V/A;++a){
		for(int b=0; b<=V/B;++b){
			if( V < a*A+b*B){
				break;
			}
			for(int c=0; c<=V/C;++c){
				if( V == a*A+b*B+c*C ){
					if( ans == -1 || ans > a+b+c){
						ans = a+b+c;
					}
				}else if( V < a*A+b*B+c*C){
					break;
				}
			}
		}
	}
	return ans;
}

int main(void){
    std::cin.tie(0); 
    std::ios::sync_with_stdio(false);
    std::cout << std::fixed;//
    //cout << setprecision(10);//
	

	int H,I,J,K;
	cin>>H>>I>>J>>K;
	int ans=-1,tans;
	for(int i=1;i<=28;++i){
		for(int j=i+1;j<=29;++j){
			for(int k=j+1;k<=30;++k){
				int dp[100];
				rep(count,31)dp[count]=1<<28;
				dp[0]=1;
				rep(count,31){
					if(dp[count] != 0){
						dp[count+i] = min( dp[count+i],dp[count]+1 );
						dp[count+j] = min( dp[count+j],dp[count]+1 );
						dp[count+k] = min( dp[count+k],dp[count]+1 );
					}
				}
				if(dp[H] != 0 && dp[I] != 0 && dp[J] != 0 && dp[K] != 0){
					tans = dp[H] + dp[I] + dp[J] + dp[K] -4 ;
					if(ans == -1 || ans > tans){
						ans = tans;
					}
				}
			}
		}
	}
	stringstream ss;
	ss << ans;
	P(ss.str());
    return 0;
}