#include<iostream>
#include<stdio.h>
#include<string>
#include<algorithm>

using namespace std;

int main() {
	int i = 0, a[6];
	double s = 0;

	for (i = 0; i < 6; i++) {
		cin >> a[i];
	}

	sort(a, a + 6);

	for (i = 0; i < 4; i++) {
		s += a[i + 1];
	}

	printf("%.2lf\n", s/4);

	return 0;
	
}