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.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Scanner;
import java.io.*;

public class Main {
	public static void main(String[] args) throws FileNotFoundException {
		// Scanner read = new Scanner(new FileInputStream(new
		// File("input.txt")));
		// PrintWriter out = new PrintWriter(new File("output.txt"));
		Scanner read = new Scanner(System.in);
		int n = read.nextInt(), a =read.nextInt(), b =read.nextInt();
		System.out.println(Math.min(n - a, b +1));
	}
}