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 JAVA):

Solution:
import java.util.Scanner;
import java.io.PrintWriter;

//import java.util.Arrays;
//import java.lang.Comparable;

//import java.lang.StringBuffer;

//import java.util.LinkedList;

public class Main {
    
    static Scanner in = new Scanner(System.in);
    static PrintWriter out = new PrintWriter(System.out);
    //static StringBuffer sb = new StringBuffer();
    //static LinkedList<Integer> list = new LinkedList<Integer>();
    
    public static void main(String[] args) {
        int n = in.nextInt(), m = in.nextInt(), t = m;
        boolean[] b = new boolean[m];
        for(int i = 0; i < n; i++) {
            int d = in.nextInt()-1, f = in.nextInt();
            for(int j = d; j < f; j++) {
                if(!b[j]) {
                    b[j] = true;
                    t--;
                }
            }
        }
        out.println(t);
        for(int i = 0; i < m; i++)
            if(!b[i])
                out.print(i + 1 + " ");
        out.close();
    }
}