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:
def solution(m, segments):
    points = list(range(1,m+1))
    for i in range(0,len(segments)):
        seg1 = segments[i][0]
        seg2 = segments[i][1]+1
        seg = list(range(seg1, seg2))
        same = list(set(seg) & set(points))
        for j in range(len(same)):
            points.remove(same[j])
    return (points)

def main():
    segments = []
    n, m = map(int, input().split())
    for i in range(0,n):
        segment = list(map(int, input().split()))
        segments.append(segment)
    result = solution(m, segments)

    l = len(result)

    print(l)
    if l != 0:
        ans = ' '.join(map(str, result))
        print(ans)
    return (result)
    
    
if __name__ == "__main__":
    main()