#include <iostream>
#include <fstream>
#include <cstdlib>
#include <iomanip>
#include <cmath>

using namespace std;

long i,j,k,l,t;
long n,m;
double maxdis,o;

struct city
{
	double x,y;
};

city city1[100001],city2[100001];

int main()
{
	ifstream fin("faraway.in");
	ofstream fout("faraway.out");
	
	fin>>t;
	
	for (l=0;l<t;l++)
	{
		fin>>n>>m;
		for (i=1;i<=n;i++)
			fin>>city1[i].x>>city1[i].y;
		for (i=1;i<=m;i++)
			fin>>city2[i].x>>city2[i].y;
		
		maxdis=0;
		for (i=1;i<=1000000;i++)
		{
			j=rand()%(n+1);
			k=rand()%(m+1);
			o=sqrt(pow(city1[j].x-city2[k].x,2)+pow(city1[j].y-city2[k].y,2));
			if (o>maxdis)
				maxdis=o;
		}
		fout<<setiosflags(ios::fixed)<<setprecision(3)<<maxdis<<endl;
	}
	
	fin.close();
	fout.close();
	
	return 0;
}