program yaoyuandejuli;
var
  t,k,i,j,n,m:longint;
  max:int64;
  ax,ay,bx,by:array[1..100000]of longint;
begin
  assign (input,'faraway.in');
  reset (input);
  assign (output,'faraway.out');
  rewrite (output);
    readln (t);
    for k:=1 to t do
    begin
      readln (n,m);
      for i:=1 to n do
        readln(ax[i],ay[i]);
      for i:=1 to m do
        readln(bx[i],by[i]);
      max:=0;
      for i:=1 to n do
        for j:=1 to m do
          if sqr(ax[i]-bx[j])+sqr(ay[i]-by[j])>max then
            max:=sqr(ax[i]-bx[j])+sqr(ay[i]-by[j]);
      writeln (extended(sqrt(max)):0:3);
    end;
  close (input);
  close (output)
end.