#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <map>
#include <set>
#include <stdio.h>
#include <cstring>
#include <queue>
#include <stack>
#include <functional>
#include <math.h>
#include <iomanip>
using namespace std;
#define Would
#define you
const int INF = 999999999;
const int MOD = 1e9 + 7;

int main() {
	int k[10];
	for (int i = 0; i < 6; ++i) { cin >> k[i]; }
	sort(k, k + 6);
	printf("%.2f\n", (double)(k[1] + k[2] + k[3] + k[4]) / 4);
}