#include <bits/stdc++.h>
using namespace std;
int main()
{
int n, x;
scanf("%d", &n);
vector<int> a(n);
for(int& ai: a)
scanf("%d", &ai);
scanf("%d", &x);
sort(a.begin(), a.end());
int total = accumulate(a.begin(), a.end(), 0);
for(int i = 0; i < n; i++)
if(total - a[i] >= x)
total -= a[i];
else
{
printf("%.7f", (double)total / (n - i));
break;
}
return 0;
}
