> //北极通讯网络 
> //#include<bits/stdc++.h>
> #include<cmath>
> #include<iostream>
> #include<cstdio>
> #include<algorithm>
> #include<vector>
> using namespace std;
> struct Node{
> 	int b,e;
> 	double w;
> 	bool operator <(const Node &a) const{
> 		return w<a.w;
> 	}
> };
> struct OP{
> 	int x,y;
> }op[510];
> int N,S,P,fa[510];
> double ans=0;
> int Find(int x){
> 	if(fa[x]==x) return x;
> 	return fa[x]=Find(fa[x]);
> }
> void Join(int x,int y){
> 	fa[Find(x)]=Find(y);
> }
> vector<Node > edge;
> int main(){
> 	cin>>N;
> 	for(int i=0;i<N;i++){
> 		cin>>S>>P;
> 		for(int j=1;j<=P;j++){
> 			cin>>op[j].x>>op[j].y;
> 			fa[j]=j;
> 			for(int k=1;k<j;k++){
> 				Node tmp;
> 				tmp.b=j,tmp.e=k,tmp.w=sqrt(double((op[j].x-op[k].x)*(op[j].x-op[k].x)+(op[j].y-op[k].y)*(op[j].y-op[k].y)));
> 				edge.push_back(tmp);
> 			}
> 		}
> 		sort(edge.begin(),edge.end());
> 		int cnt=0;
> 		for(int j=0;j<edge.size();j++){
> 			//cout<<edge[j].b<<" "<<edge[j].e<<" "<<edge[j].w<<endl;
> 			if(Find(edge[j].b)!=Find(edge[j].e)){
> 				Join(edge[j].b,edge[j].e);
> 				cnt++;
> 				ans=edge[j].w;
> 			}
> 			if(cnt==P-S) break;
> 		}
> 		printf("%.2lf\n",ans);
> 	}
> 	return 0;
> }