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.BufferedOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Scanner;

public class C {

	// @SuppressWarnings("resource")
	public static void main(String[] args) throws IOException {

		Scanner sc = new Scanner(System.in);
		PrintStream ps = new PrintStream(new BufferedOutputStream(System.out));
		int n = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		int one = n - a;
		ps.print(Math.min(one, b + 1));
		ps.flush();
		ps.close();
		sc.close();
	}

	static long g(long a, long b) {
		if (b == 0)
			return a;
		return g(b, a % b);
	}
}
