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;

public class main {

	public static void main(String[] args) {
		Scanner input = new Scanner (System.in) ;
		int a,b,n ;
		n = input.nextInt() ;
		a = input.nextInt() ;
		b = input.nextInt() ;
		int count = 0 ;
		for(int i = 0; i <= b; i ++ ){
			if ((a+i+1)<=n){
				count ++ ; 
			}
		}
				System.out.println(count);
		input.close();
	}

}
