Points in Segments

Description:

Input:

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

The next $$$n$$$ lines contain two integers each $$$l_i$$$ and $$$r_i$$$ ($$$1 \le l_i \le r_i \le m$$$) — 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.

Sample Input:

3 5
2 2
1 2
5 5

Sample Output:

2
3 4 

Sample Input:

1 7
1 7

Sample 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.