#include <iostream>
#include <math.h>
#include <iomanip>

using namespace std;

int main() {
	
	
	int min = 999,max = -1;
	
	int a;
	double sum = 0;
	for(int i = 0; i < 6; i++) {
		cin >> a;
		if(min > a)min = a;
		if(max < a)max = a;
		sum += a;
	}
	sum -= min + max;
	sum /= 4.0;
	cout << fixed << setprecision(2) << sum << endl;
	
	
	
}