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 position{
    public static void main(String ar[])
    {
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        int a=sc.nextInt();
        int b=sc.nextInt();
        int count=0;
        
        do{ 
            if(n-(a+1)<=b)
            {
            if(n>=(a+1))
            {
                count++;
                a++;
            }
            }
            else a++;
        }while(n>=(a+1));
        
        
        System.out.println(count);

    }
}