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

int main() {
	vector<int> s(6);
	for (auto &x : s) cin >> x;
	cout << (accumulate(s.begin(), s.end(), 0) - *max_element(s.begin(), s.end()) - *min_element(s.begin(), s.end())) / 4.0 << endl;
}