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 A_The_number_of_positions_124 {

	public static void main(String[] args) {

		Scanner input = new Scanner(System.in);
		int n = input.nextInt();
		int a = input.nextInt();
		int b = input.nextInt();

		int ans=0;
		while (true) {
			if ((n - a-1) <= b) {
				ans++;
				a++;
			}else {
				a++;
			}
			if(a==n) {
				break;
			}
		}
		System.out.println(ans);
	}
}