#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
using namespace std;

#define ll long long
#define INF (1 << 30)
#define INFLL (1LL << 60)

int main() {
	double num[6];
	double ans = 0.0;
	for(int i = 0;i < 6;i++){
		cin >> num[i];
	}
	sort(num, num + 6);
	for(int i = 1;i < 5;i++){
		ans += num[i];
	}
	cout << ans / 4.0 << endl;
	return 0;
}