#include <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <algorithm>
#include <sstream>
#include <iostream>
#include <string>
#include <cstdio>
#include <cmath>

using namespace std;

int main() {

	double S[6];
	for (int i = 0; i < 6; i++) {
		cin >> S[i];
	}
	sort(S, S+6);
	double sum = 0;
	for (int i = 1; i < 5; i++) {
		sum += S[i];
	}

	printf("%.2f\n", sum/4);
	return 0;
}