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.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.*;

 public class Chewbecca {
    static class Reader
    {
    BufferedReader r;
    StringTokenizer str;
    Reader()
    {
        r=new BufferedReader(new InputStreamReader(System.in));
    }
    Reader(String fileName) throws FileNotFoundException
    {
        r=new BufferedReader(new FileReader(fileName));
    }
    public String getNextToken() throws IOException
    {
        if(str==null||!str.hasMoreTokens())
    {
        str=new StringTokenizer(r.readLine());
    }
        return str.nextToken();
    }
    public int nextInt() throws IOException
    {
        return Integer.parseInt(getNextToken());
    }
    public long nextLong() throws IOException
    {
        return Long.parseLong(getNextToken());
    }
    public double nextDouble() throws IOException
    {
        return Double.parseDouble(getNextToken());
    }
    public String nextString() throws IOException
    {
        return getNextToken();
    }
    public int[] intArray(int n) throws IOException
    {
        int a[]=new int[n];
        for(int i=0;i<n;i++)
            a[i]=nextInt();
       
        return a;
       
    }
    public long[] longArray(int n) throws IOException
    {
        long a[]=new long[n];
        for(int i=0;i<n;i++)
            a[i]=nextLong();
       
        return a;
       
    }
    public String[] stringArray(int n) throws IOException
    {
        String a[]=new String[n];
        for(int i=0;i<n;i++)
            a[i]=nextString();
       
        return a;
       
    }
    public long gcd(long a, long b) {
        if(b == 0){
            return a;
        }
        return gcd(b, a%b);
    }
    }
   
    public static void main(String args[]) throws IOException{

       Reader r=new Reader();
       PrintWriter pr=new PrintWriter(System.out,false);

       int num=r.nextInt();
       int f=r.nextInt();
       int b=r.nextInt();
       if((f+b+1)<=num)
       {
           pr.print(b+1);          
       }
       else pr.print(num-f);
       
       //pr.print(ans);
       
       pr.flush();
       pr.close();
       
    }
 }
