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 The_number_of_positions {

    /**
     * 
     * 2011-12-12
     * @author froest
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
//      int count = 100;
//      while(count-->0){
        Scanner scan = new Scanner(System.in);
        int a[] = new int[3];
        int i;
        for(i = 0;i < 3; i++){
            a[i] = scan.nextInt();
        }
        int res = a[0] - a[1];
        if(res >= a[2] + 1){
            System.out.println(a[2] + 1);
        }else{
            System.out.println(res);
        }
        }
    //}
}