#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

int main() {
  vector<double> s(6);
  for (int i = 0; i < 6; ++i) {
    cin >> s[i];
  }
  sort(s.begin(), s.end());

  double sum = 0;
  for (int i = 1; i < 5; ++i) {
    sum += s[i];
  }
  cout << fixed << setprecision(2) << sum / 4 << '\n';
  return 0;
}