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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;


public class Main {
    public static void main(String []args) throws IOException{
        BufferedReader br = new BufferedReader (new InputStreamReader (System.in));
        String cad= br.readLine();
        StringTokenizer toke = new StringTokenizer(cad);
        int n=Integer.parseInt(toke.nextToken()),
            a=Integer.parseInt(toke.nextToken()),
            b=Integer.parseInt(toke.nextToken());
        int cont=0;
        for(int i=1;i<=n;i++){
            //System.out.println(i);
            int dif=n-i;
            if(a<i && dif<=b)cont++;
        }
        System.out.println(cont);
    }
}
