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.math.BigInteger;
import java.util.*;


public class Template
{
    private static BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
    static String readln() throws IOException
    {
        String line = input.readLine();
        return line;
    }

    public static void main(String[] args) throws IOException
    {
        solution();
    }


    public static void solution() throws IOException {
        String [] nab = readln().split(" ");
        int n = Integer.parseInt(nab[0]);
        int a = Integer.parseInt(nab[1]);
        int b = Integer.parseInt(nab[2]);
        System.out.println(n - Math.max(a + 1, n - b) + 1);
    }
}
