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;

/**
 * https://codeforces.com/problemset/problem/124/A
 */
public class Problem124A {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        scanner.useDelimiter(System.lineSeparator());
        String[] input = scanner.next().split(" ");
        scanner.close();
        int n = Integer.parseInt(input[0]);
        int a = Integer.parseInt(input[1]);
        int b = Integer.parseInt(input[2]);
        int count = 0;
        for (int i = 0; i < n; i++) {
            if (i + 1 > a && n - (i + 1) <= b) {
                count++;
            }
        }
        System.out.println(count);
    }
}
