#include<iostream>
#include<vector>
#include<string>
#include<cstdio>
#include<algorithm>
using namespace std;
int main(){
    int x;
    vector<int> num;
    for(int i=0;i<6;i++){
        cin >> x;
        num.push_back(x);
    }
    sort(num.begin(),num.end());
    int sum=0;
    for(int i=1;i<5;i++){
        sum+=num[i];
    }
    printf("%.2f",sum/4);
    return 0;
}