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 Cf {

	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int a,b,n,i,x,y,cnt=0;
		n=sc.nextInt();
		a=sc.nextInt();
		b=sc.nextInt();
		for(i=1;i<=n;i++)
		{
			x=i-1;
			y=n-i;
			//System.out.println(x+" "+y);
			if(x>=a && y<=b) {
				//System.out.println(i);
				cnt++;
			}
		}
		System.out.print(cnt);
	}

}