#include<bits/stdc++.h>
#define COGS
using namespace std;
const int maxn=10010;
int n,k,le[maxn],ans,l,r=-1;
double temp;
inline void in(){
	#ifdef COGS
	freopen("cable.in","r",stdin);
	freopen("cable.out","w",stdout);
	#endif
	scanf("%d%d",&n,&k);
	for (int i=1;i<=n;i++){
		scanf("%lf",&temp);
		le[i]=float(temp*100.0);
		r=max(r,le[i]);
	}
	r++;
}
inline bool check(int x){
	int ans=0;
	for (int i=1;i<=n;i++){
		ans+=le[i]/x;
	}
	if (ans>=k) return 1;
	else return 0;
}
inline void deal(){
	//printf("l=%d,r=%d\n",l,r);
	while(l+1<r){
		int mid=(l+r)/2;//printf("%d\n",mid);
		if (check(mid)) l=mid;
		else r=mid;
	}
}
inline void p(){
	printf("%.2lf",l/100.0);
}
int Main(){
	//freopen("a.txt","r",stdin);
	in();
	deal();
	p();
	return 0;
}
int main(){;}
int xlm=Main();