#include <iostream>
#include <vector>
#include <algorithm>
#include <cstdio>
#define repeat(i,n) for (int i = 0; (i) < (n); ++(i))
typedef long long ll;
using namespace std;
const long double eps = 1e-10;
int main() {
    int n; cin >> n;
    vector<int> ls(n); repeat (i,n) cin >> ls[i];
    ll k; cin >> k;
    long double l = 0, r = *max_element(ls.begin(), ls.end());
    repeat (iteration,1000) {
        long double m = (l + r) / 2;
        ll cnt = 0;
        repeat (i,n) cnt += floorl(ls[i] / m);
        (k <= cnt ? l : r) = m;
    }
    printf("%.14Lf\n", l);
    return 0;
}