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 A {

    void run(){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
        boolean[] p = new boolean[n+1];
        boolean[] q = new boolean[n+1];
        for(int i=n-b;i<=n;i++)p[i]=true;
        for(int i=a+1;i<=n;i++)q[i]=true;
        int res = 0;
        for(int i=1;i<=n;i++)if(p[i]&&q[i]){
            res++;
        }
        System.out.println(res);
    }
    
    public static void main(String[] args) {
        new A().run();
    }
}