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

int main() {
    int sum = 0;
    int mx = 0;
    int mn = 100;
    for (int i = 0; i < 6; i++) {
        int a; cin >> a; sum += a;
        mx = max(mx, a);
        mn = min(mn, a);
    }
    cout << fixed << setprecision(2) << (sum - mx - mn) / 4.0 << endl;
    return 0;
}