#include <iostream>
#include <iomanip>
#include <algorithm>
using namespace std;
int s[6];
int min_s = 100, max_s, sum;

int main() {
  for (int i = 0; i < 6; i++) {
    cin >> s[i];
    sum += s[i];
    min_s = min(s[i], min_s);
    max_s = max(s[i], max_s);
  }
  sum -= min_s + max_s;
  cout << fixed << setprecision(2) << sum / 4.0 << endl;
}