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 whatever; // 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 final class Ideone
{
    public static void main (String[] args) throws java.lang.Exception
    {
        
        Scanner in = new Scanner(System.in);
        int n,a,b;
        n=in.nextInt();
        a=in.nextInt();
        b=in.nextInt();
        System.out.println(n-Math.max(a+1,n-b)+1);}}
        
                
                
            
            
        
        