#include <iostream>
#include <algorithm>
#include <numeric>
#include <iomanip>
using namespace std;

int main() {
    double S[6];
    for(int i=0; i<6; ++i) {
        cin >> S[i];
    }
    sort(begin(S), end(S));
    cout << fixed << setprecision(2) << accumulate(begin(S)+1, end(S)-1, 0.0) / 4.0 << endl;
}