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.
/*
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 * and open the template in the editor.
 */

//package a92;

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

public class Main
{
   public static void main(String[] args) throws IOException
   {
      new Main().run();
   }

   StreamTokenizer in;
   PrintWriter out;

   String nextString() throws IOException
   {
      in.nextToken();
      return (String)in.sval;
   }

   int nextInt() throws IOException
   {
      in.nextToken();

      return (int)in.nval;
   }


   void run() throws IOException
   {
      in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
      out = new PrintWriter(new OutputStreamWriter(System.out));
      solve();
      out.flush();
   }

   void solve() throws IOException
   {
      int n = nextInt();
      int a = nextInt();
      int b = nextInt();
      int c = n;
      c = c - a;
      if (c>b+1){
      c = c - (c-b-1);
      }
      out.print(c);
   }
}