#include<bits/stdc++.h>
#define int long long
using namespace std;

double a[1000000];
double sum;
double r,l;
main(){
    double n,m;
    cin >> n >> m;
    for(int i=1;i<=n;i++)cin>>a[i],a[i] = a[i]*100;
    double mid = (r+l)/2,r=100*100,l=0;
    while(r > l+1){
        mid = (r+l)/2;
        int total = 0;
        for(int i=1;i<=n;i++)total += a[i]/mid;
        if(mid == 0)break;
        if(total == mid){
            cout << fixed << setprecision(2) <<l/100 << endl;
            return 0;
        } 
        if(total < m)r = mid;
        else l = mid;
        total = 0;
    }
    cout << fixed << setprecision(2) <<l/100 << endl;
    return 0;
}