#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <algorithm>
//---------------------------
using namespace std;
//---------------------------
#define REP(i,n) for(int i = 0; i < (n); i++)
#define P(x) cout << (x) << "\n"
//---------------------------


int main(){
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);


  vector<int> v(6);
  REP(i,6){cin >> v[i];}
  sort(v.begin(),v.end());
  v.erase(v.begin());
  v.pop_back();
  int sum = 0;
  REP(i,4){
    sum += v[i];
  }
  printf("%.2f\n", sum / 4.00);

  return 0;
}