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.* ;
import java.util.*;

import static java.lang.Math.* ;
import static java.util.Arrays.* ;

public class A {
    
    public static void main(String[] args) throws IOException {
        
        new A().solveProblem();
        
        out.close();
    }

    static Scanner in = new Scanner(new InputStreamReader(System.in));
    //static BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    static PrintStream out = new PrintStream(new BufferedOutputStream(System.out));
    
    
    public void solveProblem() {        

        int n = in.nextInt() ;
        int a = in.nextInt() ;
        int b = in.nextInt() ;
        
        b = min( n-1-a, b ) ;
        out.println(b+1) ;
    }

       
}