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.Scanner;

public class A {

	private A (Scanner sc) throws Throwable {
		int n = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		solve(n, a, b);
	}
	
	private void solve (int n, int a, int b) throws Throwable {
		print (Math.min(b+1, n-a));
	}
	
	////////////////////////////////////////////////////////////////////////////////////

	private void print (Object o) {
		System.out.println(o);
	}
	
	public static void main(String[] args) throws Throwable {		
		Scanner sc = new Scanner(System.in);
		new A(sc);
	}	
}
