Petr stands in line of n people, but he doesn't know exactly which position he occupies. He can say that there are no less than a people standing in front of him and no more than b people standing behind him. Find the number of different positions Petr can occupy.

Input

The only line contains three integers n, a and b (0 ≤ a, b < n ≤ 100).

Output

Print the single number — the number of the sought positions.

Examples

Input

3 1 1


Output

2


Input

5 2 3


Output

3

Note

The possible positions in the first sample are: 2 and 3 (if we number the positions starting with 1).

In the second sample they are 3, 4 and 5.
import java.util.*;


public class Main{
    public static void main(String[] args){
        Scanner s=new Scanner(System.in);
        
        int n=s.nextInt();
       int a=s.nextInt();
       int b=s.nextInt();
       int i;
       int c=0;
       for(i=1;i<=n;i++){
           if(i<=a){
               continue;
           }
           else if(i<n-b){
               continue;
           }
           else{
               c=c+1;
           }
       }
       System.out.print(c);
            
        
    }
    }