#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
	vector<int> s;
	s.resize(6);
	for (int i = 0; i<6; i++) {
		cin >> s[i];
	}
	sort(s.begin(), s.end());
	s.pop_back();
	s.erase(s.begin());
	int sum = 0;
	for (int i = 0; i<4; i++) {
		sum += s[i];
	}
	cout << fixed << setprecision(2) << (double)sum / 4 << endl;

	return 0;
}