/*
 * Solution Template for Jump on Platforms
 * 
 * Australian Informatics Olympiad 2026
 * 
 * This file is provided to assist with reading of input and writing of output
 * for the problem. You may modify this file however you wish, or
 * you may choose not to use this file at all.
 */

import java.io.*;

class Solution {

  /* N is the number of platforms. */
  private static int N;
  /*
   * P contains the platform positions. The array starts from 0, so the
   * positions are P[0] to P[N-1].
   */
  private static int P[] = new int[200005];

  private static int answer;
  /*
   * Read the next token from the input file.
   * Tokens are separated by whitespace, i.e., spaces, tabs and newlines.
   * If end-of-file is reached then an empty string is returned.
   */
  private static String readToken(BufferedReader in) throws IOException {
    StringBuffer ans = new StringBuffer();
    int next;

    /* Skip any initial whitespace. */
    next = in.read();
    while (next >= 0 && Character.isWhitespace((char)next))
      next = in.read();

    /* Read the following token. */
    while (next >= 0 && ! Character.isWhitespace((char)next)) {
      ans.append((char)next);
      next = in.read();
    }

    return ans.toString();
  }

  public static void main(String[] args) throws IOException {
    /* Open the input and output streams for stdin and stdout. */
    BufferedReader input_reader = new BufferedReader(new InputStreamReader(
        System.in));
    BufferedWriter output_writer = new BufferedWriter(new OutputStreamWriter(
        System.out));
    /* Read the number of platforms and their positions. */
    N = Integer.parseInt(readToken(input_reader));
    for (int i = 0; i < N; i++) {
      P[i] = Integer.parseInt(readToken(input_reader));
    }

    /*
     * TODO: Compute the length of the longest required jump and store it in
     * answer.
     */

    /* Write the answer. */
    output_writer.write(answer + "\n");

    /* Close the input_reader and output_writer. */
    input_reader.close();
    output_writer.close();
  }
}