#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <numeric>

using namespace std;

int main() {
	vector<int> s(6);
	for (int i = 0; i < 6; i++) {
		cin >> s[i];
	}
	sort(s.begin(), s.end());
	double avg = accumulate(s.begin() + 1, s.end() - 1, 0.0) / 4;
	printf("%.2f\n", avg);
	return 0;
}