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.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;

public class Main {
	public static void main(String[] args) {
		Task task = new Task();
		task.getData();
		task.solve();
		task.printAnswer();
	}
}

class Task {
	int n, a, b;
	int answer = 0;

	public void getData() {
		Scanner console = new Scanner(System.in);

		n = console.nextInt();
		a = console.nextInt();
		b = console.nextInt();

		console.close();
	}

	public void solve() {
		answer = n - Math.max(a + 1, n - b) + 1;
	}
	
	public void printAnswer() {
		System.out.print(answer);
	}
}