#include<bits/stdc++.h>
using namespace std;
#define ll long long
ll n , m;
vector<ll>l1;
ll k;
bool check(double x)
{
    long long cnt = 0;
    for(int i=1;i<=n;i++)
        cnt += (long long)(l1[i]/x);

    return cnt >= k;
}
int main()
{
    ll i , j , t;
    ios::sync_with_stdio(0); cin.tie(0);
    cin >> n;
    l1.assign(n+5 , 0);
    for(i = 1 ; i <= n ; i++) cin >> l1[i];
    cin >> k;
    double l = 0 , r = *max_element(l1.begin() , l1.end());
    for(i = 0 ;  i < 100 ; i++)
    {
        double mid = (l + r) / 2;
        if(check(mid)) l = mid;
        else r = mid;
    }
    cout << l;
}