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

using namespace std;
int main(){

    vector<int>V;
    for(int i=0;i<6;i++){
        int d;
        cin>>d;
        V.push_back(d);
    }
    sort(V.begin(),V.end());
    double f=0;
    for(int i=1;i<5;i++){
        f+=V[i];
    }
    cout.precision(2);
    cout<<fixed;
    cout<<f/4<<endl;

    return 0;
}