#include <bits/stdc++.h>

using namespace std;

#define copy(from, to) copy(from.begin(), from.end(), back_inserter(to))
#define sort(a) sort(a.begin(), a.end())
#define input_to(a) int a_i; cin >> a_i; a.push_back(a_i);

int main() {
  vector<int> s;
  for (int i = 0; i < 6; ++i) {
    input_to(s);
  }

  sort(s);
  printf("%.2f", (s[1] + s[2] + s[3] + s[4]) / 4.0);
}