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

using ld = long double;
using ll = long long;

int main(void) {
	cout << fixed << setprecision(30);
	
	int N;
	cin >> N;
	vector<ld> L(N);
	for(int i = 0; i < N; ++i) cin >> L[i];
	ll K;
	cin >> K;
	
	ld ok = 0, ng = 2e10;
	for(int _ = 0; _ < 100; ++_) {
		ld mid = (ng + ok) / 2;
		
		ll cnt = 0;
		for(int i = 0; i < N; ++i) cnt += static_cast<ll>(floor(L[i] / mid));
		
		(cnt >= K ? ok : ng) = mid;
	}
	
	cout << ok << "\n";
	
	return 0;
}