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.OutputStreamWriter;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.Random;
import java.util.StringTokenizer;

public class Thenumberofpositions {

  static BufferedReader in;
  static PrintWriter out;
  static StringTokenizer tok;

  static void solve() throws Exception {
    int n = nextInt(), a = nextInt(), b = nextInt();
    out.println(Math.min(n - a, b + 1));
  }

  public static void main(String args[]) {
    try {
      in = new BufferedReader(new InputStreamReader(System.in));
      out = new PrintWriter(new OutputStreamWriter(System.out));
      solve();
      in.close();
      out.close();
    } catch (Throwable e) {
      e.printStackTrace();
      System.exit(1);
    }
  }

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

  static int[] nextIntArray(int len, int start) throws IOException {
    int[] a = new int[len];
    for (int i = start; i < len; i++)
      a[i] = nextInt();
    return a;
  }

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

  static long[] nextLongArray(int len, int start) throws IOException {
    long[] a = new long[len];
    for (int i = start; i < len; i++)
      a[i] = nextLong();
    return a;
  }

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

  static double[] nextDoubleArray(int len, int start) throws IOException {
    double[] a = new double[len];
    for (int i = start; i < len; i++)
      a[i] = nextDouble();
    return a;
  }

  static BigInteger nextBigInteger() throws IOException {
    return new BigInteger(next());
  }

  static String next() throws IOException {
    while (tok == null || !tok.hasMoreTokens()) {
      tok = new StringTokenizer(in.readLine());
    }
    return tok.nextToken();
  }

  static String nextLine() throws IOException {
    tok = new StringTokenizer("");
    return in.readLine();
  }

  static void shuffleArray(long[] array) {
    Random random = new Random();
    for (int i = array.length - 1; i > 0; i--) {
      int index = random.nextInt(i + 1);
      long temp = array[index];
      array[index] = array[i];
      array[i] = temp;
    }
  }

}
