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.Scanner;

/**
 *
 * @author PICARI_2017
 */
public class Test7 {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
       Scanner scan = new Scanner(System.in);
       int n = scan.nextInt();
       int a = scan.nextInt();
       int b = scan.nextInt();
       int ans = (n-a);
       if(ans >b+1){
           ans = b+1;
       }
       ans =Math.max(0, ans);
       System.out.print(ans);
    }
    
}