#include<iostream>
using namespace std;
int v[4];
int dp[32];
int f( int i, int j, int k){
  for( int l=0;l<=30;l++)dp[l]=0x1fffffff-30;
  dp[0]=0;
  for( int l = 1;l<=30;l++){
    if(i<=l)dp[l]=min(dp[l],dp[l-i]+1);
    if(j<=l)dp[l]=min(dp[l],dp[l-j]+1);
    if(k<=l)dp[l]=min(dp[l],dp[l-k]+1);
  }
}
    
int main(void){
  cin>>v[0]>>v[1]>>v[2]>>v[3];
  int res = 200;
  for(int i=1;i<=30;i++){
    for(int j=i+1;j<=30;j++){
      for(int k=j+1;k<=30;k++){
        f(i,j,k);
        res = min(res, dp[v[0]]+dp[v[1]]+dp[v[2]]+dp[v[3]]);

        //        for( int l = 0;l <= 30;l++)cout<<dp[l]<<" ";
        //        cout<<endl;
        //        cout<<"res = "<<res<<endl;

      }
    }
  }
  cout<<res<<endl;
  return 0;
}