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.
/* package codechef; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
public class Codechef
{
	public static void main (String[] args) throws java.lang.Exception
	{
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		String input[]=br.readLine().split(" ");
		int n=Integer.parseInt(input[0]);
		int a=Integer.parseInt(input[1]);
		int b=Integer.parseInt(input[2]);
		int x=a+1;
		int y=n-b;
		int z=Math.max(x,y);
		int ans=n-z+1;
		System.out.println(ans);
	}
}
