#include<iostream>
#include<algorithm>
#include <vector>
#include<cmath>
#include<iomanip>
using namespace std;
typedef long long int lont;
int main() {
	vector<float>vec(6);
	for (int ia = 0; ia < 6; ia++) {
		cin >> vec.at(ia);
	}
	sort(vec.begin(), vec.end());
	std::cout <<std::setprecision(5)<< (vec.at(1) + vec.at(2) + vec.at(3) + vec.at(4)) / 4 << endl;
}