#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <iomanip>
#include <cmath>
using namespace std;
#define diff(x,y) ((x > y) ? (x - y) : (y - x))

int main() {
	int sum = 0;
	vector <int> num(6);
	for (int i = 0; i < 6; i++)
		cin >> num[i];
	sort(num.begin(), num.end());
	for (int i = 1; i < 5; i++)
		sum += num[i];
	cout << fixed << setprecision(2) << (double)sum / 4 << endl;
	return 0;
}