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.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;
import java.util.Stack;
import java.util.StringTokenizer;

public class Main {

  
    public static Scanner input = new Scanner(System.in);

    public static void main(String[] args)
            throws IOException {

        // BufferedReader buffer=new BufferedReader(new InputStreamReader(System.in));
        //  String str;
//         while((str=buffer.readLine())!=null){
        PrintWriter writer = new PrintWriter(new OutputStreamWriter(System.out));
//while(input.hasNextLine()){
    //  BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); 
int n=input.nextInt();
int a=input.nextInt();
int b=input.nextInt();
        writer.println(Math.min(n-a-1, b)+1); 
        writer.flush();
}
}
