#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <queue>
#include <cmath>
#include <climits>
#include <iomanip>
#include <set>
#include <map>
using namespace std;
typedef long long ll;
int main(){
    vector<ll> a(6);
    for(int i = 0;i < 6;i++)cin >> a[i];
    sort(a.begin(),a.end());
    double res = 0;
    for(int i = 1;i < 5;i++)res += a[i];
    res /= (double)4;
    cout << res << endl;
}