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

#define rep(i,a,b) for(int i=a;i<b;i++)
#define int long long
const int inf = 100100100100100;
const int mod = 1000000007;


signed main(){
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);

    int n;
    cin >> n;
    int arr[n];
    rep(i,0,n) cin >> arr[i];
    int k;
    cin >> k;

    double left = 0;
    double right = 1e13;

    rep(i,0,100){
        double mid = (left + right)/2;

        int cnt = 0;
        rep(j,0,n){
            cnt += (int)(arr[j]/mid);
        }
        if(cnt >= k){
            left = mid;
        }else{
            right = mid;
        }

    }
    cout << fixed << setprecision(10) <<left << endl;



}