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;
import java.util.Arrays;
//import java.util.Math;
public class mitul
{
       public static void main(String args[])
       {
            
            Scanner scan = new Scanner(System.in);
            int n = scan.nextInt();
            int a = scan.nextInt();
            int b = scan.nextInt();
            int count=0;
            for(int i=a+1;i<=n;i++)
            {
                   for(int j=n-b;j<=n;j++)
                   {
                          if(i==j)
                          {
                                 count++;
                          }
                   }
            }
            System.out.println(count);
       }
}