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.
/*
  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.
*/

import java.util.Scanner;

public class NumPositions {

    public static void main(String[] args) {
    	Scanner scan = new Scanner(System.in);
        int n;
        int a;
        int b;
        int sols = 0;
		
		NumPositions np = new NumPositions();
		
		n = scan.nextInt();
		a = scan.nextInt();
		b = scan.nextInt();
			
		for(int	 B = n - b; B <= n; B++) {
			if(B > a)
				sols++;
		}
		
		System.out.println(sols);
    }
}
