#include <algorithm>
#include <iomanip>
#include <iostream>
#include <vector>

using namespace std;

int main(int argc, const char* argv[])
{
	vector<int> Ss(6);
	for (auto&& s : Ss) {
		cin >> s;
	}
	sort(Ss.begin(), Ss.end());
	double sum = 0.0;
	for (int i = 0; i < 6 - 2; i++) sum += Ss[i + 1];
	cout << fixed << setprecision(2) << sum / 4.0 << endl;
	return 0;
}