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.io.*;
import java.util.*;

public class div_3_501_a {
	public static void main(String args[]){
		FScanner in = new FScanner();
		PrintWriter out = new PrintWriter(System.out);
		//int t = in.nextInt();
		//while(t-->0) { 
        int n=in.nextInt();
        int u=in.nextInt();
        int a[]=new int[u+1];
        for(int i=1;i<=n;i++)
        {
        	int l=in.nextInt();
        	int r=in.nextInt();
        	for(int j=l;j<=r;j++)
        	{
        		a[j]++;
        	}
        }
        int c=0;
        ArrayList<Integer> al=new ArrayList<Integer>();
        for(int i=1;i<u+1;i++)
        {
        	if(a[i]==0)
        	{
        		c++;
                al.add(i);
        	}
        }
        out.println(c);
        for(int i:al)
        	out.print(i+" ");




		//}
		out.close();
	}

    static class FScanner {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer sb = new StringTokenizer("");
 
		String next(){
			while(!sb.hasMoreTokens()){
				try{
					sb = new StringTokenizer(br.readLine());
				} catch(IOException e){ }
			}
			return sb.nextToken();
		}
		String nextLine(){
			try{ return br.readLine(); } 
			catch(IOException e) { } return "";
		}
 
		int nextInt(){
			return Integer.parseInt(next());
		}
 
		long nextLong() {
			return Long.parseLong(next());
		}
 
		int[] readArray(int n) {
			int a[] = new int[n];
			for(int i=0;i<n;i++) a[i] = nextInt();
			return a;
		}
 
		float nextFloat(){
		return Float.parseFloat(next());
		}
		
		double nextDouble(){
		return Double.parseDouble(next());
		}
	}
}