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.*;
public class Main {
	static Scanner sc = new Scanner(System.in);
	static int n, a,b;
	public static void main(String[] args) {
		n = sc.nextInt();
		a = sc.nextInt();
		b = sc.nextInt();
		solve();
	}
	static void solve(){
		boolean[] array = new boolean[n+1];
		for(int i = 0; i < array.length; i++){
			array[i] = true;
		}
		for(int i = 0; i <= a; i++){
			array[i] = false;
		}
		for(int i = 0; i < array.length; i++){
			if(n-i > b)array[i] = false;
		}
		int res = 0;
		for(int i = 1; i < array.length; i++){
			if(array[i] == true)res++;
		}
		System.out.println(res);
	}

}