#include<stdio.h>
#include<stdlib.h>

int comp(const void *a, const void *b){
    if(*(int *)a < *(int *)b){
        return 1;
    }
    else if(*(int *)a == *(int *)b){
        return 0;
    }

    return -1;
}

double binary_search(int n, int x[], long long k){
    double l = 0, r = 1000000000;

    for(int aiueo = 0;aiueo < 50;aiueo++){
        long long current_num = 0;
        double mid = (l + r) / 2.0;

        for(int i = 0;i < n;i++){
            current_num += (int)(x[i] / mid);
        }

        if(k <= current_num){
            l = mid;
        }
        else{
            r = mid;
        }
    }
    return l;
}

int main(){
    int n;
    long long k;
    scanf("%d", &n);
    int length[n];

    for(int i = 0;i < n;i++){
        scanf("%d", &length[i]);
    }
    scanf("%lld", &k);
    printf("%f\n", binary_search(n, length, k));

    return 0;
}