#include<iomanip> #include<iostream> #include<cstdio> #include<cmath> using namespace std; int n,k; #define int long long double l[1000000]; int check(double x){ int sum=0; for(int i=0;i<n;i++){ sum+=(double)l[i]/x; } return sum; } double binary_search(double start,double end){ double ans=-1; while(start<end){ double mid=(start+end)/2; int c=check(mid); if(c<k){ end=mid; }else if(c>k){ start=mid; }else{ start=mid; if(abs(mid-ans)<0.01) return ans; ans=mid; } } return ans; } signed main(){ cin>>n>>k; for(int i=0;i<n;i++) cin>>l[i]; int k=(double)binary_search(1,1e5)*100; cout<< fixed << setprecision(2)<<(double)k/100; return 0; }