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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

/**
 * Date 03.11.2011
 * Time 19:09:57
 * Author Woodey
 * $
 */

public class A {

	private void Solution() throws IOException {
		int n = nextInt(), a = nextInt(), b = nextInt();
		System.out.println(Math.min(b+1, n-a));
	}

	public static void main(String[] args) {
		new A().run();
	}

	BufferedReader in;
	StringTokenizer tokenizer;

	public void run() {
		try {
			in = new BufferedReader(new InputStreamReader(System.in));
			tokenizer = null;
			Solution();
			in.close();
		} catch (Exception e) {
			e.printStackTrace();
			System.exit(1);
		}
	}

	int nextInt() throws IOException {
		return Integer.parseInt(nextToken());
	}

	String nextToken() throws IOException {
		while (tokenizer == null || !tokenizer.hasMoreTokens())
			tokenizer = new StringTokenizer(in.readLine());
		return tokenizer.nextToken();
	}
}
