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

public class numpositions {
    
    public static void main (String [] args) throws IOException
    {
        Scanner scan = new Scanner (System.in);
        StringTokenizer s = new StringTokenizer(scan.nextLine());
        int n = Integer.parseInt (s.nextToken());
        int a = Integer.parseInt (s.nextToken());
        int b = Integer.parseInt (s.nextToken());
        int count = 0;
        for (int i = 1; i <= n; i ++)
        {
            if (i-1 >= a && n-i <= b)
                count ++;
        }
        System.out.println (count);
    }
}