Arctic Network

#include <bits/stdc++.h>
using namespace std;
#define F(W) for(int i(0);i<W;++i)
#define FF(W) for(int j(0);j<W;++j)
#define FT(I,W) for(int k(I);k<W;++k)
#define ZERO (1e-10)
#define EPS ZERO
#define INF (1<<30)
#define LINF (1LL<<60)
#define NINF (-(1<<30))
#define MP(A,B) make_pair(A,B)
#define CL(A,I) (memset(A,I,sizeof(A)))
#define ADD(A,B,V) (g[A].push_back(B),g[B].push_back(A),v[A].push_back(V),v[B].push_back(V))
#define add(A,B) (g[A].push_back(B),g[B].push_back(A))
#define DEB printf("DEB!\n");
#define DEX printf("DD2!\n");
#define EQ(A,B) (A+ZERO>B&&A-ZERO<B)
typedef long long ll;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef pair<int, int> ii;
#define REP(i, n) for (int i = 0; i < n; i++)
#define IN(n) int n; cin >> n;
#define PB push_back
#define MX (512)
double dst(double AX,double AY,double BX,double BY){
    return sqrt(pow(AX-BX,2)+pow(AY-BY,2));
}
double x[MX],y[MX];
int tt,K,N;
struct eg{
    eg(int f,int t,double v):f(f),t(t),v(v){}
    int f,t;
    double v;
    bool operator<(const eg&r)const{return v>r.v;}
};
priority_queue<eg> q;
int W[MX],C[MX];
void rc(int c,int t){
    W[t]+=W[c];
    W[c]=-1;
    C[c]=t;
}
int geco(int a){
    return a==C[a]?a:geco(C[a]);
}
bool con(int a,int b){
    C[a]=geco(a);C[b]=geco(b);
    if(C[a]==C[b])return 0;
    rc(C[b],C[a]);
    return 1;
}
double st(int H){
    double S(0);
    while(H--){
        con(q.top().f,q.top().t);
        S=q.top().v;
        while(!q.empty()&&geco(q.top().f)==geco(q.top().t))q.pop();
    }
    while(!q.empty())q.pop();
    return S;
}
int main(void){
    for(scanf("%d",&tt);tt--;){
        scanf("%d%d",&K,&N);
        F(N)scanf("%lf%lf",x+i,y+i);
        F(N)FT(i+1,N)q.push(eg(i,k,dst(x[i],y[i],x[k],y[k])));
        iota(C,C+N,0);CL(W,0);
        if(K<=1)printf("%.2lf\n",st(N-1));
        else printf("%.2lf\n",st(N-K));
    }
    return 0;
}