#include <iostream>
#include <cstring>
#include <iomanip> 
using namespace std;


long long int N = 0;
long long int L[300000];
long long int K = 0;

bool C(double x) { // c(x):xの長さの棒をK本作れるかどうか
	long long int num = 0;
	for (long long int i = 0; i < N; i++) {
		num += (long long int)(L[i] / x);
	}
	if (num >= K) return true;
	else return false;
}


int main()
{
	memset(L, 0, sizeof(L));
	cin >> N;
	for (long long int i = 0; i < N; i++) {
		cin >> L[i];
	}
	cin >> K;

	double lb = 0;
	double ub = 2000000000;

	for (int i = 0; i < 1000; i++) {
		double mid = (lb + ub) / 2;
		if (C(mid)) lb = mid;
		else ub = mid;
	}

	cout << fixed << setprecision(14) << ub << endl;
    return 0;
}