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

long long n, a[200005], LaPiece, X;
long double l, r, mid;

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i];
    cin >> LaPiece;

    l = 0; r = 1000000000;
    while (l <= r) {
        mid = (l + r) / 2; X = 0;
        for (int i = 1; i <= n; i++) X += a[i] / mid;
        if (X >= LaPiece) l = mid + 0.000000001;
        else r = mid - 0.000000001;
    }
    cout << setprecision(10) << l;
}