#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll inf = 100100100100100;
const ll mod = 1000000007;


int main(){
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);
    ll n;
    cin >> n;
    vector<ll> arr(n);
    for(int i=0;i<n;i++)cin >> arr.at(i);
    ll k;
    cin >> k;
    double left = 0;
    double right = 1e13;
    for(int i=0;i<100;i++){
        double mid = (left + right)/2;

        ll cnt = 0;
        for(int j=0;j<n;j++){
            cnt += (ll)(arr.at(j)/mid);
        }
        if(cnt >= k){
            left = mid;
        }else{
            right = mid;
     }
    }
    cout << fixed << setprecision(10) <<left << endl;
}