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.*;

public class Position{

	public static int findPositions(int n, int a, int b)
	{
		int count=0;
		for(int i=0; i<n; i++)
		{
			int front = i;
			int back = (n-1)-i;
			if((front >= a) && (back <= b))
				count++;
		}
		return count;
	}

	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		int n= sc.nextInt();
		int a= sc.nextInt();
		int b= sc.nextInt();

		int pos = findPositions(n, a, b);
		System.out.println(pos);
	}

}