#include <stdio.h>
#include <algorithm>
using namespace std;
using ll = long long;

//394
int main() {
	int s[6];
	for (int i = 0; i < 6; i++)
		scanf("%d", s + i);
	sort(s, s + 6);

	double ave = 0.0;
	for (int i = 1; i < 5; i++)
		ave += s[i];
	printf("%.2lf\n", ave / 4);
}