#include <iostream>
#include <cstdlib>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;
int main(){
    vector<double> v;
    double x;
    double score;
    for(int i = 0; i < 6; i++){
        cin >> x;
        v.push_back(x);
    }
    sort(v.begin(), v.end());
    score = (v[1] + v[2] + v[3] + v[4]) / 4;
    printf("%.2f", score); 
    cout << endl; 

    return 0;
}