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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Scanner;
import java.util.StringTokenizer;


/**
 *
 * @author Ahmad
 */
public class JavaApplication1 {

    
    public static void main (String[] args) throws IOException, Exception {
      FastReader console = new FastReader();
      int n = console.nextInt() ; 
      int a = console.nextInt() ;
      int b = console.nextInt() ;
      int x[] = new int [n] ;  
      for (int i=0 ; i<x.length ; i++){
          x[i]=1 ; 
      }
      int count = 0 ;  
      int f = n ;
      for (int i=0 ; i<a ; i++){
          x[i]=0 ; 
      }
      for (int i=0; i<x.length ; i++){
          f-- ; 
          if (f<=b&&x[i]!=0){
              count++ ;
          }
      }
        System.out.println(count);
    }
}
class FastReader {

    BufferedReader br;
    StringTokenizer st;

    public FastReader() {
        br = new BufferedReader(new InputStreamReader(System.in));
    }
    String next() {
        while (st == null || !st.hasMoreElements()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return st.nextToken();
    }

    int nextInt() {
        return Integer.parseInt(next());
    }

    long nextLong() {
        return Long.parseLong(next());
    }

    double nextDouble() {
        return Double.parseDouble(next());
    }

    String nextLine() {
        String str = "";
        try {
            str = br.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return str;
    }
}
