#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    vector<int> vc;
    for (int i = 0; i < 6; i++) {
        int j;
        cin >> j;
        vc.push_back(j);
    }
    sort(vc.begin(), vc.end());
    double avg = (vc.at(1) + vc.at(2) + vc.at(3) + vc.at(4)) / 4.0;
    printf("%.2f\n", avg);
    return 0;
}