#include <iostream>
#include <algorithm>
#include <vector>>
#include <cstdio>
using namespace std;
#define all(v) (v).begin(),(v).end()
#define rep(i,n) for(int i=0;i<(n);i++)

int main(void){
	vector<int> s(6);
	rep(i, 6) cin >> s[i];
	sort(all(s));
	double sum = 0;
	for (int i = 1; i < 5 ; ++i){
		sum += s[i];
	}
	printf("%.2f\n", sum / 4.0);
	return 0;
}