#include <iostream>
#include <iomanip>
#include <algorithm>
#include <vector>
using namespace std;
int main(void) {
	vector<int> s(6);
	for (int i = 0; i < 6; ++i) cin >> s[i];
	sort(s.begin(), s.end());
	double sum = 0;
	for (int i = 1; i < 5; ++i) sum += s[i];
	sum /= 4;
	cout << fixed << setprecision(2) << sum << endl;
	return 0;
}