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{

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner key = new Scanner(System.in);
		int n = key.nextInt();
		int a = key.nextInt();
		int b = key.nextInt();

		int counter = 0;
		int before = 0;
		int after = n - 1;

		for (int i = 0; i < n; i++) {
			if (before >= a && after <= b)
				counter++;
			before++;
			after--;
		}
		System.out.println(counter);

	}

}
