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

int main() {
	vector<int> v(6);
	for (int i = 0; i < 6; i++) {
		cin >> v.at(i);
	}

	double avg = 0;
	sort(v.begin(), v.end());
	for (int i = 1; i < v.size() - 1; i++) {
		avg += v.at(i);
	}
	avg /= 4.0;

	cout << fixed << setprecision(2) << avg << endl;
}