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.
/**
 * @author Saikot Majumdar
 * @since 20/12/2020 11:07
 * codeforces.practice
 */

import java.io.*;
import java.util.StringTokenizer;

public class TheNumberOfPositions {

    private static BufferedReader br;
    private static StringTokenizer st;
    private static PrintStream out;

    public static void main(String[] args) throws IOException {
        br = new BufferedReader(new InputStreamReader(System.in) /*new FileReader("file.in")*/);
        out = new PrintStream(System.out /*new FileOutputStream("file.out")*/);

        int N = nextInt();
        int A = nextInt(); // no less than A
        int B = nextInt(); // no more than B

        if((N - A) > B) {
            out.println(B + 1);
        } else {
            out.println(N - A);
        }

        // out.println(nextInt()); //Example usage
    }

    private static int nextInt() throws IOException {
        return Integer.parseInt(next());
    }

    private static long nextLong() throws IOException {
        return Long.parseLong(next());
    }

    private static double nextDouble() throws IOException {
        return Double.parseDouble(next());
    }

    private static String next() throws IOException {
        while (st == null || !st.hasMoreTokens()) {
            if (!br.ready()) throw new IOException("BufferedReader not ready");
            st = new StringTokenizer(br.readLine().trim());
        }
        return st.nextToken();
    }
}
