#include "bits/stdc++.h"
using namespace std;

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