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.util.Scanner;


public class A124 {

    private static Scanner input;

    public static void main(String[] args) {
        input = new Scanner(System.in);
        int n, a, b, counter = 0;
        n = input.nextInt();
        a = input.nextInt();
        b = input.nextInt();
        for(int i = a+1; i <= a + b + 1; i++)
            if(i <= n)
                counter ++;
        System.out.println(counter);
    }
}