#include<cstdio>

 #include<iostream>

 using namespace std;

 int ans, n, k, a[], max_l;

 inline void er_fen(){

     int l = , r = max_l;

     while(l <= r){

         int cnt = ;

         int mid = (l + r) >> ;

         for(int i = ; i <= n; i++){

             cnt += a[i] / mid;

         }

         if(cnt >= k){

             ans = max(ans, mid);

             l = mid + ;

         }

         else r = mid - ;

     }

 }

 int main(){

     while(scanf("%d%d", &n, &k) != EOF){

         max_l = -, ans = ;

         for(int i = ; i <= n; i++){

             double len;

             scanf("%lf", &len);

             a[i] = len * ;

             max_l = max(max_l, a[i]);

         }

         er_fen();

         printf("%.2f\n", (double) ans / 100.0);

     }

     return ;

 }