from random import getrandbits, randrange
from string import ascii_lowercase, ascii_uppercase
import sys
from math import ceil, floor, sqrt, pi, factorial, gcd, log, log10, log2, inf, cos, sin
from copy import deepcopy, copy
from collections import Counter, deque, defaultdict
from heapq import heapify, heappop, heappush
from itertools import (
    accumulate,
    chain,
    product,
    combinations,
    combinations_with_replacement,
    permutations,
)
from bisect import bisect, bisect_left, bisect_right
from functools import lru_cache, reduce
from decimal import Decimal, getcontext
from typing import List, Tuple, Optional


inf = float("inf")


class Inf:
    def __init__(self, value):
        self.value = value

    def __lt__(self, other):
        return False

    def __le__(self, other):
        if isinstance(other, Inf):
            return True
        return False

    def __gt__(self, other):
        if isinstance(other, Inf):
            return False
        return True

    def __ge__(self, other):
        return True

    def __eq__(self, other):
        return isinstance(other, Inf) and self.value == other.value

    def __repr__(self):
        return f"{self.value}"

    def __add__(self, other):
        return Inf(self.value) if isinstance(other, Inf) else self

    def __sub__(self, other):
        return Inf(self.value) if isinstance(other, Inf) else self

    def __mul__(self, other):
        return Inf(self.value) if isinstance(other, Inf) else self


def ceil_div(a, b):
    return (a + b - 1) // b


def isqrt(num):
    res = int(sqrt(num))
    while res * res > num:
        res -= 1
    while (res + 1) * (res + 1) <= num:
        res += 1
    return res


def int1(s):
    return int(s) - 1


from types import GeneratorType


def bootstrap(f, stack=[]):
    def wrapped(*args, **kwargs):
        if stack:
            return f(*args, **kwargs)
        else:
            to = f(*args, **kwargs)
            while True:
                if type(to) is GeneratorType:
                    stack.append(to)
                    to = next(to)
                else:
                    stack.pop()
                    if not stack:
                        break
                    to = stack[-1].send(to)
            return to

    return wrapped


import sys
import os

input = lambda: sys.stdin.readline().rstrip("\r\n")

print = lambda *args, end="\n", sep=" ": sys.stdout.write(
    sep.join(map(str, args)) + end
)


def II():
    return int(input())


def MII(base=0):
    return map(lambda s: int(s) - base, input().split())


def LII(base=0):
    return list(MII(base))


def NA():
    n = II()
    a = LII()
    return n, a


def read_graph(n, m, base=0, directed=False, return_edges=False):

    g = [[] for _ in range(n)]
    edges = []
    for _ in range(m):
        a, b = MII(base)
        if return_edges:
            edges.append((a, b))
        g[a].append(b)
        if not directed:
            g[b].append(a)
    if return_edges:
        return g, edges
    return g


def read_graph_with_weight(n, m, base=0, directed=False, return_edges=False):

    g = [[] for _ in range(n)]
    edges = []
    for _ in range(m):
        a, b, w = MII()
        a, b = a - base, b - base
        if return_edges:
            edges.append((a, b, w))
        g[a].append((b, w))
        if not directed:
            g[b].append((a, w))
    if return_edges:
        return g, edges
    return g


def read_edges_from_ps():
    ps = LII(1)
    edges = []
    for i, p in enumerate(ps, 1):
        edges.append((p, i))
    return edges


def iterate_tokens():
    for line in sys.stdin:
        for word in line.split():
            yield word


tokens = None


def NI():
    global tokens
    if tokens is None:
        tokens = iterate_tokens()
    return int(next(tokens))


def LNI(n):
    return [NI() for _ in range(n)]


def yes(res):
    print("Yes" if res else "No")


def YES(res):
    print("YES" if res else "NO")


def pairwise(a):
    n = len(a)
    for i in range(n - 1):
        yield a[i], a[i + 1]


def factorial(n):
    return reduce(lambda x, y: x * y, range(1, n + 1))


def cmin(dp, i, x):
    if x < dp[i]:
        dp[i] = x


def cmax(dp, i, x):
    if x > dp[i]:
        dp[i] = x


def alp_a_to_i(s):
    return ord(s) - ord("a")


def alp_A_to_i(s):
    return ord(s) - ord("A")


def alp_i_to_a(i):
    return chr(ord("a") + i)


def alp_i_to_A(i):
    return chr(ord("A") + i)


d4 = [(1, 0), (0, 1), (-1, 0), (0, -1)]
d8 = [(1, 0), (1, 1), (0, 1), (-1, 1), (-1, 0), (-1, -1), (0, -1), (1, -1)]


def ranges(n, m):
    return ((i, j) for i in range(n) for j in range(m))


def rangess(a, b, c):
    return ((i, j, k) for i in range(a) for j in range(b) for k in range(c))


def valid(i, j, n, m):
    return 0 <= i < n and 0 <= j < m


def ninj(i, j, n, m):
    return [(i + di, j + dj) for di, dj in d4 if valid(i + di, j + dj, n, m)]


def gen(x, *args):
    if len(args) == 1:
        return [x] * args[0]
    if len(args) == 2:
        return [[x] * args[1] for _ in [0] * args[0]]
    if len(args) == 3:
        return [[[x] * args[2] for _ in [0] * args[1]] for _ in [0] * args[0]]
    if len(args) == 4:
        return [
            [[[x] * args[3] for _ in [0] * args[2]] for _ in [0] * args[1]]
            for _ in [0] * args[0]
        ]


list2d = lambda a, b, v: [[v] * b for _ in range(a)]
list3d = lambda a, b, c, v: [[[v] * c for _ in range(b)] for _ in range(a)]


class Debug:
    def __init__(self, debug=False):
        self.debug = debug
        cur_path = os.path.dirname(os.path.abspath(__file__))
        self.local = os.path.exists(cur_path + "/.cph")

    def get_ic(self):
        if self.debug and self.local:
            from icecream import ic

            return ic
        else:
            return lambda *args, **kwargs: ...


class Mo:
    def __init__(self, N):
        self.N = N
        self.Q = 0
        self.left = []
        self.right = []

    def add_query(self, l, r):
        self.left.append(l)
        self.right.append(r + 1)
        self.Q += 1

    def calculate(self):
        block_size = self.N // (min(self.N, int(self.Q**0.5 + 0.5)))
        t = (self.N + block_size - 1) // block_size
        B = [[] for _ in range(t)]

        left = self.left
        right = self.right

        for q in range(self.Q):
            B[left[q] // block_size].append(q)

        for i in range(t):
            B[i].sort(key=lambda q: right[q], reverse=i % 2)
        return B


ic = Debug(1).get_ic()
for _ in range(II()):
    n, l = MII()
    ps = [LII() for _ in range(n)]
    mo = Mo(l + 1)
    for l, r in ps:
        mo.add_query(l, r)
    B = mo.calculate()
    print(n)
    for b in B:
        for q in b:
            print(*ps[q], sep=" ")