#include <iostream>
#include <iomanip>
#include <algorithm>
#include <vector>

using ldouble = long double;

void solve() {
    std::vector<ldouble> xs(6);
    for (auto& x : xs) std::cin >> x;
    std::sort(xs.begin(), xs.end());

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

    std::cout << std::fixed << std::setprecision(2)
              << s / 4 << std::endl;
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}