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:
n, m = [int (i) for i in input().split()]
skobki = []
for i in range(n):
	l, r = [int (i) for i in input().split()]
	skobki.append((l,r))
skobki.sort()
A = []
cur_l, cur_r = skobki[0]
for l,r in skobki[1:]:
	if l <= cur_r < r:
		cur_r = r
	elif cur_r < l:
		A.append((cur_l, cur_r))
		cur_l, cur_r = l, r
A.append((cur_l, cur_r))
cur = 0
res = []
for x in range(1, m + 1):
	l, r = A[cur]
	if x < l or x > r:
		res.append(x)    
	elif x == r:
		cur = min(cur + 1, len(A) - 1)
print(len(res))
for i in res:
	print(i, end = ' ')