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 Triangle {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);        
        String line = in.nextLine();
        in.close();

        String[] nums = line.split(" ");
        int queue = Integer.parseInt(nums[0]);
        int before = Integer.parseInt(nums[1]);
        int after = Integer.parseInt(nums[2]);
        int count = 0;
        int possible = queue - before;

        for (int i = 1; i <= possible; i++) {
            if ((possible - i) <= after) {
                count++;
            }
        }
        System.out.println(count);
    }
}