import sys
#sys.setrecursionlimit((1<<19)-1)
#import pypyjit
#pypyjit.set_param('max_unroll_recursion=-1')
input=sys.stdin.buffer.readline

T=int(input())
for i in range(T):
    N,L=map(int,input().split())
    pos=[tuple(map(int,input().split())) for i in range(N)]
    rp=[]
    cnt=0
    bac=max(1,L//500)
    for x,y in pos:
        p=1
        if (x//bac)%2:
            p=-1
        rp.append((x//bac,(y//bac)*p,cnt))
        cnt+=1
    rp.sort()
    print(N)
    for _,_,i in rp:
        print(*pos[i])