#include <iostream>
#include <algorithm>
#include <cstdio>
using namespace std;

int main() {
	double s[6];
	
	cin>>s[0]>>s[1]>>s[2]>>s[3]>>s[4]>>s[5];
	
	sort(s,s+6);
	
	printf("%.2f\n",(s[1]+s[2]+s[3]+s[4])/4);
	
	return 0;
}