#include <iostream>
#include <iomanip>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <list>
#include <stack>
#include <queue>

#define REP(i,n) FOR(i, 0, n)
#define REPC(x,c) for(const auto& x:(c))
#define FOR(i, b, e) for(int i = (int)(b); i < (int)(e); ++i)
#define VS vector<string>
#define VI vector<int>
#define VVI vector<vector<int>>
#define ALL(x) (x).begin(),(x).end()
#define PAIR pair<int,int>

using  ll = long long;

using namespace std;

int main() {
	ll n, k;
	cin >> n;
	VI v(n);
	REP(i, n) { cin >> v[i]; }
	cin >> k;

	double l = 0, r = *max_element(ALL(v));
	double mid;
	REP(i,100){
		mid = (l + r) / 2;
		ll count = 0;
		REPC(x, v) { count += (ll)(x / mid); }
		((count >= k) ? l : r) = mid;
	}
	cout << fixed << mid << endl;
}