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 Tester {
	public static void main(String[] ar)
	{
		int n,a,b,ctr=0;
		Scanner s=new Scanner(System.in);
		n=s.nextInt();
		a=s.nextInt();
		b=s.nextInt();
		int[] arr=new int[n];
		for(int i=0;i<n;i++)
			arr[i]=0;
		for(int i=a;i<n;i++)
			arr[i]+=1;
		for(int i=n-1;i>=n-1-b && i>=0;i--)
			arr[i]+=1;
		for(int i=0;i<n;i++)
		{
			if(arr[i]==2)
				ctr++;
		}
		System.out.println(ctr);
	}

}
