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.
 */


import java.util.Scanner;

/**
 *
 * @author DELL
 */
public class Codeforces92 {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
       
        Scanner nera = new Scanner(System.in);
        
        int n = nera.nextInt();
        int a= nera.nextInt();
        int b= nera.nextInt();
        
        
        
        if(n-a>b){
            System.out.println(b+1);
        }else if(n-a<b){
            System.out.println(n-a);
        }else if(n-a==b){
            System.out.println(b);
        }
        
        
    }
}
