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.io.PrintWriter;

public class Solution {
    public static void main(String[] args) throws NumberFormatException, IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

        String[] sp = in.readLine().split(" ");
        int n = Integer.parseInt(sp[0]);
        int a = Integer.parseInt(sp[1]);
        int b = Integer.parseInt(sp[2]);

        int min = Math.max(a + 1, n - b);
        int max = n;

        PrintWriter out = new PrintWriter(System.out);

        if (min == max)
            out.print(1);
        else if (min > max)
            out.print(0);
        else
            out.print(max - min + 1);

        out.close();
    }
}
