#include <iostream>
#include <string>
#include <vector>
#include <cmath>
#include <fstream>
#include <set>
#include <utility>
#include <algorithm>

using namespace std;

int max(int x, int y) {
	int a;
	(x > y) ? a = x : a = y;
	return a;
}

int min(int x, int y) {
	int a;
	(x < y) ? a = x : a = y;
	return a;
}

int main() {
	int v[6];
	for (int i = 0; i < 6; i++)cin >> v[i];
	sort(&v[0], &v[6]);

	double sum = 0;
	for (int i = 1; i < 5; i++)sum += v[i];
	printf("%.2f", sum/4);


	return 0;
}