#include <iostream>
#include <cstdlib>
#include <vector>
#include <algorithm>
#include <cmath>
#include <iostream>
#include <iomanip>
#include <deque>

int main()
{
    std::vector<int> a;
    int d;
    for(int i = 0; i < 6; i++){
        std::cin >> d;
        a.push_back(d);
    }
    std::sort(a.begin(), a.end());
    int sum = a[1] + a[2] + a[3] + a[4];
    
    std::cout << std::fixed << std::setprecision(2) << sum / 4.0 << std::endl;
    return 0;
}