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.io.InputStreamReader;
import java.util.Scanner;



public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(new InputStreamReader(System.in));
		
		int n = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		int res = 0;
		for (int i=0; i<n; i++){
			if ((i+1>a)&&(n-i-1<=b)){
				res++;
			}
		}
		System.out.println(res);
	}
}


