#include <iostream>#include <cstring>#include <iomanip>#include <algorithm>#include <cmath>#include <cstdio>using namespace std;const int MAXN = 510;const int INF = 1000010;int n, m;int Edge[MAXN][MAXN];void Inite(){int i, j;int X[MAXN], Y[MAXN];memset(Edge, 0, sizeof(Edge));cin >> m >> n;for(i = 0; i < n; ++i)cin >> X[i] >> Y[i];for (i = 0; i < n; ++i){for(j = i+1; j < n; ++j){Edge[i][j] = (X[i] - X[j]) * (X[i] - X[j]) + (Y[i] - Y[j]) * (Y[i] - Y[j]);Edge[j][i] = Edge[i][j];}}for (i = 0; i < n; ++i){for (j = 0; j < n; ++j){if(Edge[i][j] == 0)Edge[i][j] = INF;}}}void Prim(){int lowcost[MAXN];int dist[MAXN];int sum = 0;int i, j;for (i = 0; i < n; ++i){lowcost[i] = Edge[0][i];}lowcost[0] = -1;memset(dist, 0, sizeof(dist));for(i = 1; i < n; ++i){int MIN = INF;int v;for(j = 0; j < n; ++j){if (lowcost[j] != -1 && lowcost[j] < MIN){v = j;MIN = lowcost[j];}}dist[sum++] = MIN;lowcost[v] = -1;for (j = 0; j < n; ++j){if (lowcost[j] != -1 && lowcost[j] > Edge[v][j]){lowcost[j] = Edge[v][j];}}}sort(dist, dist+sum);cout << setiosflags(ios::fixed) << setprecision(2) <<sqrt((double)dist[ sum-m ])<<endl;}int main(){int T;cin>>T;while (T--){Inite();Prim();}return 0;}
