import io
import sys
from collections import defaultdict, deque, Counter
from itertools import permutations, combinations, accumulate
from heapq import heappush, heappop
from bisect import bisect_right, bisect_left
from math import gcd
import math

_INPUT = """\
6
2
4 6
0 1
4 2
5 3
3 1
3 1000000000
0 0
1000000000 0
1000000000 1000000000
"""

def input():
  return sys.stdin.readline()[:-1]

def solve(test):
  T=int(input())
  for _ in range(T):
    N,L=map(int, input().split())
    A=[list(map(int, input().split())) for _ in range(N)]
    B=max(1,int(L/int(N**.5)+1))
    ans=[]
    A=sorted([(A[i][0]//B,A[i][1]//B if A[i][0]//B%2==0 else -A[i][1]//B,A[i][0],A[i][1]) for i in range(N)],reverse=True)
    for i in range((L-1)//B+2):
      if i%2==0:
        for j in range((L-1)//B+1):
          ans.append((i*B,j*B))
          while A and A[-1][0]==i and A[-1][1]==j:
            ans.append((A[-1][2],A[-1][3]))
            A.pop()
      else:
        for j in reversed(range((L-1)//B+1)):
          ans.append((i*B,j*B))
          while A and A[-1][0]==i and A[-1][1]==-j:
            ans.append((A[-1][2],A[-1][3]))
            A.pop()
    print(len(ans))
    for i in range(len(ans)): print(*ans[i])

def random_input():
  from random import randint,shuffle
  N=randint(1,10)
  M=randint(1,N)
  A=list(range(1,M+1))+[randint(1,M) for _ in range(N-M)]
  shuffle(A)
  return (" ".join(map(str, [N,M]))+"\n"+" ".join(map(str, A))+"\n")*3

def simple_solve():
  return []

def main(test):
  if test==0:
    solve(0)
  elif test==1:
    sys.stdin = io.StringIO(_INPUT)
    case_no=int(input())
    for _ in range(case_no):
      solve(0)
  else:
    for i in range(1000):
      sys.stdin = io.StringIO(random_input())
      x=solve(1)
      y=simple_solve()
      if x!=y:
        print(i,x,y)
        print(*[line for line in sys.stdin],sep='')
        break

#0:提出用、1:与えられたテスト用、2:ストレステスト用
main(0)