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:
st = input()
n = int(st.split()[0])
m = int(st.split()[1])

a = [0] * n
Ox = [0] * (m + 1)

for i in range(n):
    a[i] = [0] * 2
    st = input()
    a[i][0] = int(st.split()[0])
    a[i][1] = int(st.split()[1])

for i in range(n):
    l = a[i][0]
    r = a[i][1]
    if r == l:
        Ox[r] = 1
    else:
        for x in range(l, r + 1):
            Ox[x] = 1

answer = []
count = 0
for i in range(1, m + 1):
    if Ox[i] == 0:
        count = count + 1
        answer.append(i)

print(count)
for i in range(count):
    print(answer[i], end=' ')