#include <bits/stdc++.h>
using namespace std;

#define int long long

signed main()
{
	int sum = 0, mi = LLONG_MAX/2, ma = 0;
	for (int i = 0; i < 6; i++)
	{
		int s;
		cin >> s;
		mi = min(mi, s);
		ma = max(ma, s);
		sum += s;
	}
	printf("%.2f\n", (sum - mi - ma)/4.0);
	return 0;
}