B"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 . 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. 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. 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. "...