#include<iostream>
#include<iomanip>

using namespace std;
int main() {
	int A[6], t, i, j;
	cin >> A[0] >> A[1] >> A[2] >> A[3] >> A[4] >> A[5];
	for (i = 0; i < 6; i++) {
		for (j = i + 1; j < 6; j++) {
			if (A[i] > A[j]) {
				t = A[i];
				A[i] = A[j];
				A[j] = t;
			}
		}
	}
	int sum = 0;
	double ave;
	sum = A[1] + A[2] + A[3] + A[4];
	ave = double(sum) / 4;
	cout << fixed << setprecision(2) << ave << "\n";

	return 0;
}