#define _CRT_SECURE_NO_WARNINGS
#include <cstdio>
#include <iostream>
#include <string>
#include <algorithm>
typedef unsigned long long ull;
using namespace std;
int main() {
	int S[6];
	for (int i = 0; i < 6; i++) {
		cin >> S[i];
	}
	sort(S, S + 6);
	int ans = 0;
	for (int i = 1; i < 5; i++) {
		ans += S[i];
	}
	printf("%.2lf\n", (double)(ans) / 4);
}