#include <iostream>
#include <algorithm>
#include <string>
#include <cstdio>
using namespace std;

int main()
{
    int s[6];
    for (auto& x : s) cin >> x;

    sort (s, s + 6);

    int sum = 0;
    for (int i = 1; i < 5; i++) sum += s[i];

    printf("%.2f\n", sum / 4.0);

    return 0;
}