#include <bits/stdc++.h>

using namespace std;

template<typename Function> long double bisectionMethod(Function function, long double lower, long double upper) {
  for (int i = 0; i < 200; ++i) {
    long double middle = (lower + upper) / 2;
    (function(middle) <= 0 ? lower : upper) = middle;
  }
  return lower;
}

int main() {
  int n;
  cin >> n;
  vector<int> l(n);
  for (int& i : l) cin >> i;
  long long k;
  cin >> k;
  auto f = [&](double x){
    long long sum = 0;
    for (int& i : l) sum += floor(i / x);
    return sum - k + 0.5;
  };
  cout << fixed << setprecision(15) << bisectionMethod(f, numeric_limits<int>::max(), 0);
}