#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int countCuttedSticks(vector<int> sticks, double cutLength) {
    int count = 0;
    for (int stick: sticks) {
        count += (int)((double) stick / cutLength);
    }
    
    return count;
}

int main(void){
    // Your code here!
    int N;
    cin >> N;
    vector<int> sticks(N);
    for (int i=0; i < N; i++) {
        cin>>sticks[i];
    }
    long long K;
    cin>>K;
    
    double high, low, ans;
    high = *max_element(sticks.begin(), sticks.end());
    low = 0.0;
    
    if (countCuttedSticks(sticks, high) == K)
        cout << high << endl;
    else {
        while(high - low >= 0.0000000002) {
            ans = (high + low) / 2;
            if (countCuttedSticks(sticks, ans) >= K)
                low = ans;
            else
                high = ans;
        }
        
        cout << ans << endl;
    }
    
}