#include <bits/stdc++.h>
using namespace std;

double a[6];

int main() {
    for (int i = 0; i < 6; ++i) cin >> a[i];
    sort(a, a+6);
    double sum = 0;
    for (int i = 1; i < 5; ++i) sum += a[i];
    double res = sum / 4;
    cout << fixed << setprecision(2) << res << endl;
}