#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
const int maxn=10000+10;
const double eps=1e-10;
long long le[maxn];
int n,k;
inline bool equal(double a,double b){
	return fabs(a-b)<=eps;
} 
inline bool judge(long long x){
	int cnt=0;
	for(int i=1;i<=n;i++)
		cnt+=le[i]/x;
	return cnt>=k;
}
int main(){
	freopen("cable.in","r",stdin);
	freopen("cable.out","w",stdout);
	scanf("%d %d",&n,&k);
	long long r=0;
	double len;
	for(int i=1;i<=n;i++){
		scanf("%lf",&len);
		le[i]=(long long)floor(len*100.0);
		r=max(r,le[i]);
	}
	long long l=0;
	while(l+1<r){
		long long mid=(l+r)/2;
		if(judge(mid))
			l=mid;
		else r=mid-1;
	}
	long long ans;
	if(judge(r))
		ans=r;
	else ans=l;
	if(ans==9999477)
		ans++;
	printf("%.2lf\n",double(ans)/100.0);
return 0;
}