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:
leg_count, max_num = [int(x) for x in input().split()]
legs = []
for _ in range(leg_count):
    l, r = [int(x) for x in input().split()]
    legs.append((l, r))

legs = sorted(legs)

new_legs = []
l_i, r_i = legs[0]
for l_c, r_c in legs[1:]:
    if l_c <= r_i:
        r_i = max(r_c, r_i)
    else:
        new_legs.append((l_i, r_i))
        l_i, r_i = l_c, r_c
else:
    new_legs.append((l_i, r_i))

new_legs.append((max_num + 1, max_num + 2))

l, r = new_legs[0]
leg_id = 0
i = 1

vals = []
while True:
    if i > max_num:
        break
    if i < l:
        vals.append(i)
        i += 1
    elif l <= i <= r:
        i += 1
    else:
        leg_id += 1
        l, r = new_legs[leg_id]
print(len(vals))
print(' '.join(str(x) for x in vals))