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.PrintWriter;
import java.util.Scanner;

/**
 * <a href="http://codeforces.ru/problemset/problem/124/A"/>
 *
 * @author pvasilyev
 * @since 24 Dec 2013
 */
public class Problem057 {

    public static void main(String[] args) {
        final Scanner reader = new Scanner(System.in);
        final PrintWriter writer = new PrintWriter(System.out);

        solveTheProblem(reader, writer);

        reader.close();
        writer.close();
    }

    private static void solveTheProblem(final Scanner reader, final PrintWriter writer) {
        final int n = reader.nextInt();
        final int a = reader.nextInt();
        final int b = reader.nextInt();

        writer.println(Math.min(n - a, b + 1));
    }

}
