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.
/*
      mycode94
 */
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
public class testing {
    public static void main(String lol[]) throws IOException{
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        String s = in.readLine();
        String s1[] = s.split(" ");
        int count =0;
        int n = Integer.parseInt(s1[0]);
        int a = Integer.parseInt(s1[1]);
        int b = Integer.parseInt(s1[2]);
        for(int i = 0; i < n; ++i) {
            if (i >= a && n - i - 1 <= b) {
                count++;
            }
        }
        System.out.println(count);
        count =0;
    }
}