A. Points in Segmentstime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard outputYou 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 \le l_i \le r_i \le 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 \le x \le r.InputThe 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.OutputIn 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.ExamplesInput3 52 21 25 5Output23 4 Input1 71 7Output0NoteIn 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.
Input3 52 21 25 5
Output23 4 
['implementation', '*800']