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;


public class FIT {

    
    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);
        int size =in.nextInt();
        int x[]=new int [size];
        int y[]=new int [size];
        int m=in.nextInt();
        boolean f=true;
        int counter =0;
        int arr[]=new int [m];
        
        for (int i = 0; i < size; i++) {
            x[i]=in.nextInt();
            y[i]=in.nextInt();
        }
        for (int i = 1; i <= m; i++) {
            for (int j = 0; j < size; j++) {
                if (i >= x[j]  &&  i <= y[j] ) {
                    f=false;
                }
            }
            if (f) {
              arr[counter]=i;
              counter++;
            }
            f=true;
        }
        System.out.println(counter);
        for (int i = 0; i < arr.length; i++) {
            if (arr[i]==0) {
                break;
            }
            System.out.print(arr[i]+ " ");
        }
        System.out.println();
    }
    
}