#include<bits/stdc++.h>
using namespace std;

int main() {
vector<double >a(6);
double che =0;
for(int i=0;i<6;i++){
    cin >> a.at(i);
    che+=a.at(i);
}
sort(a.begin(),a.end());
che=che-a.at(0)-a.at(5);
double z=4;
double ans =che/z;
cout <<fixed <<setprecision(2);
cout <<ans <<endl;
}