#include<cstdio>

 #include<iostream>

 #include<cmath>

 #include<algorithm>

 #define M 1008

 struct data

 {

     int a1,a2,d;

 }q[M*M];

 int x[M],y[M],n,k,cnt,fa[M],sum1;

 bool cmp(data b1,data b2)

 {

     return b1.d<b2.d;

 }

 int zhao(int a1)

 {

     if(fa[a1]==a1)

       return a1;

     fa[a1]=zhao(fa[a1]);

     return fa[a1];

 }

 using namespace std;

 int main()

 {

     scanf("%d%d",&n,&k);

     for(int i=;i<=n;i++)

       scanf("%d%d",&x[i],&y[i]);

     for(int i=;i<=n;i++)

       for(int j=i+;j<=n;j++)

         {

           cnt++;

           q[cnt].a1=i;

           q[cnt].a2=j;

           q[cnt].d=(x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]);

         }

     sort(q+,q+cnt+,cmp);

     for(int i=;i<=n;i++)

       fa[i]=i;

     for(int i=;i<=cnt;i++)

       {

         int b1=zhao(q[i].a1),b2=zhao(q[i].a2);

         if(b1!=b2)

           {

             n--;

             fa[b1]=b2;

             if(n<k)

               {

                 printf("%.2lf\n",sqrt(q[i].d));

                             return ;

               }

           }

       }

 }