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

int main() {
    vector<int> s(6);
    cin >> s[0] >> s[1] >> s[2] >> s[3] >> s[4] >> s[5];
    sort(s.begin(), s.end());
    float ans = s[1] + s[2] + s[3] + s[4];
    ans /= 4;
    printf("%0.2f\n",ans);
    return 0;
}