#include<iostream>
#include<stdio.h>
using namespace std;
int main(){
    int a,b,c;
    int arr[10005],sum=0;
    float f;
    cin>>a>>b;
    for(int i=0;i<a;i++)
    {cin>>f;
    arr[i]=(f+0.005)*100;
    }
   while(++sum){
        c=0;
        for(int i=0;i<a;i++)
        c+=arr[i]/sum;
        if(c<b) break;
    }
    f=(sum-1)/100.0;
   printf("%.2lf",f);
   return 0;
}