#include<bits/stdc++.h>
using namespace std;
int a[1000001],n,k;
bool check(int x){
	int cnt=0;
	for(int i=1;i<=n;i++)
		cnt+=a[i]/x;
	return cnt>=k;
}
int main(){
	//freopen("P1577_5.in","r",stdin);
	//freopen("*.out","w",stdout);
	cin.tie(0),cout.tie(0),ios::sync_with_stdio(false);
	cin>>n>>k;
	for(int i=1;i<=n;i++){
		double t;
		cin>>t;
		a[i]=t*100;
	}
	long long l=0,r=1e18,mid,ans;
	while(l<=r){
		mid=l+r>>1;
		if(mid==0) break;
		if(check(mid)) ans=mid,l=mid+1;
		else r=mid-1;
	} 
	printf("%.2lf",ans/100.0);
	return 0;
}