#include <bits/stdc++.h>
#define int long long
#define endl '\n'
#define FOR(i, a, n) for (int i = (a); i < (n); ++i)
#define REP(i, n) FOR(i, 0, n)
using namespace std;

int N, K;
int L[200010];

bool check(double x) {
    int num = 0;
    REP (i, N) num += (int)(L[i] / x);
    return (num >= K);
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(10);

    cin >> N;
    REP (i, N) cin >> L[i];
    cin >> K;
    double ok = 0, ng = 1e9;
    REP (i, 100) {
        double m = (ok + ng) / 2;
        if (check(m)) ok = m;
        else ng = m;
    }
    cout << ok << endl;
}