#include<bits/stdc++.h>
using namespace std;
using Int = long long;
//INSERT ABOVE HERE
signed main(){
  vector<Int> s(6);
  for(Int i=0;i<6;i++) cin>>s[i];
  sort(s.begin(),s.end());
  Int x=0;
  for(Int i=1;i<5;i++) x+=s[i];
  cout<<fixed<<setprecision(2)<<(double)x/4<<endl;
  return 0;
}