Problem: You are given a set of n segments on the axis Ox, each segment has integer endpoints between 1 and m inclusive. Segments may intersect, overlap or even coincide with each other. Each segment is characterized by two integers l_i and r_i (1 ≤ l_i ≤ r_i ≤ m) — coordinates of the left and of the right endpoints. 

Consider all integer points between 1 and m inclusive. Your task is to print all such points that don't belong to any segment. The point x belongs to the segment [l; r] if and only if l ≤ x ≤ r.

Input

The first line of the input contains two integers n and m (1 ≤ n, m ≤ 100) — the number of segments and the upper bound for coordinates.

The next n lines contain two integers each l_i and r_i (1 ≤ l_i ≤ r_i ≤ m) — the endpoints of the i-th segment. Segments may intersect, overlap or even coincide with each other. Note, it is possible that l_i=r_i, i.e. a segment can degenerate to a point.

Output

In the first line print one integer k — the number of points that don't belong to any segment.

In the second line print exactly k integers in any order — the points that don't belong to any segment. All points you print should be distinct.

If there are no such points at all, print a single integer 0 in the first line and either leave the second line empty or do not print it at all.

Examples

Input

3 5
2 2
1 2
5 5


Output

2
3 4 


Input

1 7
1 7


Output

0

Note

In the first example the point 1 belongs to the second segment, the point 2 belongs to the first and the second segments and the point 5 belongs to the third segment. The points 3 and 4 do not belong to any segment.

In the second example all the points from 1 to 7 belong to the first segment.

Solution (in PYTHON3):

Solution:
import math as ma
from sys import exit
from decimal import Decimal as dec


def li():
	return list(map(int , input().split()))


# https://www.geeksforgeeks.org/multiplicative-inverse-under-modulo-m/
def modInverse(a , m):
	m0 = m
	y = 0
	x = 1
	if (m == 1):
		return 0
	while (a > 1):
		q = a // m
		t = m
		m = a % m
		a = t
		t = y
		y = x - q * y
		x = t
	if (x < 0):
		x = x + m0
	return x

m=10000019
def binomialCoefficient(n , k):
	if (k > n - k):
		k = (n - k)%m
	res = 1
	for i in range(k):
		res = (res * (n - i))%m
		res = (res * modInverse((i + 1),m))%m
	return res


def num():
	return map(int , input().split())


def nu():
	return int(input())


def find_gcd(x , y):
	while (y):
		x , y = y , x % y
	return x


n,m=num()
a=[0]*(m)
for ii in range(n):
	l,r=num()
	for i in range(l-1,r):
		a[i]=1
c=0
ll=[]
for i in range(m):
	if(a[i]==0):
		c+=1
		ll.append(i+1)
print(c)
print(*ll,sep=" ")