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;
/*
/  Môhâméd Hâshém
/  Let's Fun
/  Java 8
*/
public class Codeforces{
    public static void main(String args []){
        Scanner input = new Scanner(System.in);
        int people ,front , behined;
        people = input.nextInt();
        front = input.nextInt();
        int res = 0;
        behined = input.nextInt();
        for (int i = 1; i <= people; ++i) {
		if (i - 1 >= front&& people - i <= behined ) ++res;
	}
        
            System.out.println(res);
        
        
        
    }
}