#include <bits/stdc++.h>
using namespace std;
const int INF = 100000;
int main() {
    vector<double> S(6);
    for(int i = 0; i < 6; i++) {
        cin >> S[i];
    }
    double m = *std::min_element(S.begin(), S.end());
    double M = *std::max_element(S.begin(), S.end());
    cout << fixed << setprecision(2) << (std::accumulate(S.begin(), S.end(), 0) - M - m)/4 << endl;
    return 0;
}