#include<iostream>
#include<cstdio>
using namespace std;
typedef long long ll;
const ll mod = 10000000000;
ll n, k;
double l[200002];

bool check(double mid) {
    ll count = 0;
    for(int i= 0;i < n;i++) count += (int)(l[i] / mid); //何本分ありますか？
    //cout << "    count=" << count;
    if (count >= k) return 1;
    else return 0;
}

int main() {
    cin >> n;   //木の本数
    for(int i=0;i<n;i++) cin >> l[i];   //木のデータ
    cin >> k;   //必要な木片の本数
    double lb =0,ub = mod;  //lb:最小値    ub:最大値
    
    for(int i=0;i<100;i++) {
        double mid = (lb + ub) / 2.0;
        if (check(mid)) lb = mid;
        else ub = mid;
      //  cout << "    lb=" << lb << "     ub=" << ub << endl;
    }    
    printf("%.14f\n", ub);
    return 0;
}