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

int main() {
	std::vector<int> score(6);

	for (int i = 0; i < 6; i++) {
		std::cin >> score[i];
	}

	std::sort(score.begin(), score.end());

	int total = std::accumulate(score.begin(), score.end(), 0);

	// 最低点と最高点を取り除く
	total -= score.front() + score.back();

	double ave = total / 4.0;

	std::cout << std::fixed << std::setprecision(2) << ave << std::endl;

	return 0;
}