B'Moamen was drawing a grid of n rows and 10^9 columns containing only digits 0 and 1 . Ezzat noticed what Moamen was drawing and became interested in the minimum number of rows one needs to remove to make the grid beautiful. A grid is beautiful if and only if for every two consecutive rows there is at least one column containing 1 in these two rows. Ezzat will give you the number of rows n , and m segments of the grid that contain digits 1 . Every segment is represented with three integers i , l , and r , where i represents the row number, and l and r represent the first and the last column of the segment in that row. For example, if n = 3 , m = 6 , and the segments are (1,1,1) , (1,7,8) , (2,7,7) , (2,15,15) , (3,1,1) , (3,15,15) , then the grid is: Your task is to tell Ezzat the minimum number of rows that should be removed to make the grid beautiful. The first line contains two integers n and m ( 1 <= n, m <= 3 cdot10^5 ). Each of the next m lines contains three integers i , l , and r ( 1 <= i <= n , 1 <= l <= r <= 10^9 ). Each of these m lines means that row number i contains digits 1 in columns from l to r , inclusive. Note that the segments may overlap. In the first line, print a single integer k -- the minimum number of rows that should be removed. In the second line print k distinct integers r_1, r_2, ldots, r_k , representing the rows that should be removed ( 1 <= r_i <= n ), in any order. If there are multiple answers, print any. In the first test case, the grid is the one explained in the problem statement. The grid has the following properties: In the second test case, the given grid is as follows: '...