#include <iostream>
#include <cstdio>
#include <cassert>
#include <cstring>
#include <vector>
#include <valarray>
#include <array>
#include <queue>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <algorithm>
#include <cmath>
#include <complex>
#include <random>

using namespace std;
using ll = long long;
using ull = unsigned long long;
constexpr int TEN(int n) {return (n==0)?1:10*TEN(n-1);}

int main() {
    array<int, 6> a;
    for (int i = 0; i < 6; i++) {
        cin >> a[i];
    }
    sort(a.begin(), a.end());
    double x = a[1]+a[2]+a[3]+a[4];
    printf("%.2f\n", x/4);
    return 0;
}