#include<iostream>
#define N 10001
using namespace std;
int n,num,i,j;
int a[N];
int main()
{
	char str[200];
	int left,right,middle,sum;
	scanf("%d%d",&n,&num);
	sum=0;
	left=1;right=0;
	for(i=0;i<n;i++)
	{
		a[i]=0;
		scanf("%s",str);
		for(j=0;str[j]&&str[j]!=' ';j++){
			if(str[j]!='.')a[i]=a[i]*10+str[j]-'0';
			sum+=a[i];
			if(a[i]>right) right=a[i];
		}
	}
	if(sum<num) {printf("0.00\n");}		
	while(left<=right)
	{
		middle=(left+right)/2;
		sum=0;
		for(i=0;i<n;i++) sum+=a[i]/middle;
		if(sum<num) right=middle-1;
		if(sum>=num) left=middle+1;
	}
	printf("%.2lf\n",right*0.01);
	return 7;
}