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 {
    public static void main(String[] args) {
        TaskA Solver = new TaskA();
        Solver.Solve();
    }
    private static class TaskA {
        private void Solve() {
            Scanner in = new Scanner(System.in);
            int n = in.nextInt();
            int a = in.nextInt();
            int b = in.nextInt();
            int ans = 0;
            for (int i = 1; i <= n; i++) {
                int left = i - 1;
                int right = n - i;
                if (left >= a && right <= b)
                    ans++;
            }
            System.out.println(ans);
        }
    }
}