#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
//#include<cctype>
#include<climits>
#include<iostream>
#include<string>
#include<vector>
#include<map>
//#include<list>
#include<queue>
#include<deque>
#include<algorithm>
//#include<numeric>
#include<utility>
//#include<memory>
#include<functional>
#include<cassert>
#include<set>
#include<stack>
#include<random>

const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, -1, 0, 1};
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef pair<int, int> pii;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    vector<int> S(6);
    for (int i = 0; i < 6; i++)
        cin >> S[i];
    sort(S.begin(), S.end());
    int sum = 0;
    for (int i = 1; i < 5; i++)
        sum += 100*S[i];
    sum /= 4;
    int tmp = sum%100;
    cout << sum/100 << "." << (!tmp ? "00" : to_string(tmp)) << endl;
    return 0;
}