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.
/* +_+_+_+_+_+_+_+_+_+_+_+_+_+_+_+_+_+_+_+_+_+_+
   +_+_+_+ Captain Levi's Code +_+_+_+_+_+_+_+_+
   +_+_+_+_+_+_+_+_+_+_+_+_+_+_+_+_+_+_+_+_+_+_+  */

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

   public class codeforces{
       public static void main(String[] args){

        int i,j,k,n,t,store,flag,sum,ans;
        // float answ;
        Scanner sc = new Scanner(System.in);
        codeforces ob = new codeforces();
        n = sc.nextInt();
    
        int a,b;


        a = sc.nextInt();
        b = sc.nextInt();

        if((n-a)<=b)
        System.out.println(n-a);
        else
        System.out.println(b+1);
       }
   }