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 practice {
	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 cnt = 0; 
		for (int i = 1; i <= n; i++)
		{
			if ((i) > a && (n-i) <= b)
				cnt++;
		}
		
		System.out.println(cnt);
	}

}