Fox Ciel and her friends are in a dancing room. There are n boys and m girls here, and they never danced before. There will be some songs, during each song, there must be exactly one boy and one girl are dancing. Besides, there is a special rule:

  * either the boy in the dancing pair must dance for the first time (so, he didn't dance with anyone before); 
  * or the girl in the dancing pair must dance for the first time. 



Help Fox Ciel to make a schedule that they can dance as many songs as possible.

Input

The first line contains two integers n and m (1 ≤ n, m ≤ 100) — the number of boys and girls in the dancing room.

Output

In the first line print k — the number of songs during which they can dance. Then in the following k lines, print the indexes of boys and girls dancing during songs chronologically. You can assume that the boys are indexed from 1 to n, and the girls are indexed from 1 to m.

Examples

Input

2 1


Output

2
1 1
2 1


Input

2 2


Output

3
1 1
1 2
2 2

Note

In test case 1, there are 2 boys and 1 girl. We can have 2 dances: the 1st boy and 1st girl (during the first song), the 2nd boy and 1st girl (during the second song).

And in test case 2, we have 2 boys with 2 girls, the answer is 3.

import java.util.*;
import java.util.LinkedList;

public class tmp {
    public static void main(String [] args){
        Scanner scan = new Scanner(System.in);
        
        int n = scan.nextInt();
        int m = scan.nextInt();
        
        System.out.println((n+m-1));
        
        if(n <= m){
            for(int i=1; i<=m; i++)
                System.out.println("1 " + i);
            for(int i=2; i<=n; i++)
                System.out.println(i + " " + m);
        }else{
            for(int i=1; i<=n; i++)
                System.out.println(i + " 1");
            for(int i=2; i<=m; i++)
                System.out.println(n + " " + i);
        }
        
        
        
       
        
        
        
        
     
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
        
    }

    
    
    
    
    
    
    
    
    
    
    
    


    
    
    
    
}

class Pair implements Comparable<Pair>{
    int x,h;
    
    public Pair(int fi, int ti){
        x = fi;
        h = ti;
    }
    
    public int compareTo(Pair p){
        return x < p.x ? -1 : x==p.x ? 0 : 1;
    }
}
