#include <bits/stdc++.h>
using namespace std;
#define ll long long
ll n,m,a[200000],k;
double x,maxn;
int main(){
    cin>>n>>m;
    for(int i=1;i<=n;i++){
        cin>>x;
        a[i]=x*1000;
        k=max(k,a[i]);
    }
    ll l=1,r=k;
    while(l<=r){
        ll s=0;
        ll mid=l+(r-l)/2;
        for(int i=1;i<=n;i++) s=s+a[i]/mid;
        if(s>=m) l=mid+1,maxn=mid;
        if(s<m) r=mid-1;
    }
    printf("%.2lf",(maxn/10.0)/100.0);
    return 0;
}