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 Main {

    /**
     * @param args
     */
    public static void main(String[] args) {
        Scanner l = new Scanner(System.in);
        int n = l.nextInt();
        int a = l.nextInt();
        int b = l.nextInt();
        int  limmna = a + 1;
        int limmaxa = n;
        int  limmnb = n - b;
        int limmaxb = n;
        if(limmnb > limmaxa || limmna > limmaxa)
            System.out.println(0);
        else{
            int A = Math.max(limmna, limmnb);
            int B = Math.min(limmaxa, limmaxb);
            System.out.println(B - A + 1);
        }
    }

}
