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 Main {

    public static void main(String[] args) throws Exception {
        Scanner scan = new Scanner(System.in);
        do {
            int n = scan.nextInt(), a = scan.nextInt(), b = scan.nextInt();

            int[] array = new int[n];
            for (int i = 0; i < a; i++) {
                array[i] = -1;
            }

            if (n - a == b) {
                System.out.println(b);
            } else {
                for (int i = array.length - 1, con = 0; con <= b; i--) {
                    if (array[i] != -1) {
                        array[i] = 1;
                    }
                    con++;
                }
                int c = 0;
                for (int i = 0; i < array.length; i++) {
                    if (array[i] == 1) {
                        c++;
                    }
                }
                System.out.println(c);

            }
        } while (scan.hasNext());
    }
}
