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

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    long long n;
    cin >> n;
    vector<long long> ls(n);
    long long nmax = 0,kq = -1;
    for(long long i=0; i<n; i++) {
        cin >> ls[i];
        nmax = nmax + ls[i];
    }
    long long k;
    cin >> k;
    double l = 0, r = 1e9;
    for(long long it=0; it<100; it++) {
        double mid = (l+r)/2;
        long long tong =0;
        for(long long i=0; i<n; i++) {
            tong += (long long)ls[i]/mid;
            if(tong >= k) break;
        }
        if(tong >=k) {
            l = mid;
        }else {
            r= mid;
        }
    }
    cout << fixed << setprecision(15) << l;
}