Solution.java

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Solution {

  // Complete the toys function below.
  static int toys(int[] w) {
    Arrays.sort(w);
    int counter = 1;
    int start = 0;
    for (int i = 0; i < w.length; i++) {
      if (w[i] > w[start] + 4) {
        start = i;
        counter++;
      }
    }

    return counter;
  }

  private static final Scanner scanner = new Scanner(System.in);

  public static void main(String[] args) throws IOException {
    BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

    int n = scanner.nextInt();
    scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

    int[] w = new int[n];

    String[] wItems = scanner.nextLine().split(" ");
    scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

    for (int i = 0; i < n; i++) {
      int wItem = Integer.parseInt(wItems[i]);
      w[i] = wItem;
    }

    int result = toys(w);

    bufferedWriter.write(String.valueOf(result));
    bufferedWriter.newLine();

    bufferedWriter.close();

    scanner.close();
  }
}