Problem:
Score : 300 points

Problem Statement

You are given an integer sequence of length N, a_1,a_2,...,a_N.

For each 1≤i≤N, you have three choices: add 1 to a_i, subtract 1 from a_i or do nothing.

After these operations, you select an integer X and count the number of i such that a_i=X.

Maximize this count by making optimal choices.

Constraints

1≤N≤10^5

0≤a_i<10^5 (1≤i≤N)

a_i is an integer.

Input

The input is given from Standard Input in the following format:

N
a_1 a_2 .. a_N

Output

Print the maximum possible number of i such that a_i=X.

Sample Input 1

7
3 1 4 1 5 9 2

Sample Output 1

4

For example, turn the sequence into 2,2,3,2,6,9,2 and select X=2 to obtain 4, the maximum possible count.

Sample Input 2

10
0 1 2 3 4 5 6 7 8 9

Sample Output 2

3

Sample Input 3

1
99999

Sample Output 3

1

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Runtime Error)

import java.io.PrintStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Queue;
import java.util.Scanner;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

class a {
	public a(int i, int j, int k) {
		p1 = i;
		p2 = j;
		length = k;
	}

	int p1;
	int p2;
	int length;
}

public class Main {
	static boolean debug = true;
	static Scanner sc = new Scanner(System.in);

	public static void main(String[] args) {
		int k=sc.nextInt();
		int [] arr=new int[k];
		for(int i=0;i<k;i++)
			arr[i]=sc.nextInt();
		int res=helper(arr);
		System.out.println(res);
	}




	



	private static int helper(int[] arr) {
		// TODO Auto-generated method stub
		int[] res=new int[10003];
		for(int i=0;i<arr.length;i++){
			res[arr[i]]+=1;
			res[arr[i]+1]+=1;
			if(arr[i]==0)
				res[10002]+=1;
			else
				res[arr[i]-1]+=1;
		}
		int max=-1;
		for(int i=0;i<res.length;i++){
			max=Math.max(res[i], max);
		}

		return max;
	}


	private static void print(String string) {
		// TODO Auto-generated method stub
		if (debug)
			System.out.println(string);
	}

	private static void print(int[] data) {
		if (debug) {
			for (int i = 0; i < data.length; i++)
				System.out.println(i + ":" + data[i]);
		}
	}

	private static void print(String[] data) {
		if (debug) {
			for (int i = 0; i < data.length; i++)
				System.out.println(i + ":" + data[i]);
		}
	}

	private static void print(char[] data) {
		if (debug) {
			for (int i = 0; i < data.length; i++)
				System.out.println(i + ":" + data[i]);
		}
	}

	private static void print(double[] data) {
		if (debug) {
			for (int i = 0; i < data.length; i++)
				System.out.println(i + ":" + data[i]);
		}
	}

	private static void print(long[] data) {
		if (debug) {
			for (int i = 0; i < data.length; i++)
				System.out.println(i + ":" + data[i]);
		}
	}

	private static void print(int[][] data) {

		if (debug) {
			for (int i = 0; i < data.length; i++) {
				for (int j = 0; j < data[0].length; j++) {
					System.out.print(data[i][j] + " ");
				}
				System.out.println();
			}
		}
	}

	private static void print(long[][] data) {

		if (debug) {
			for (int i = 0; i < data.length; i++) {
				for (int j = 0; j < data[0].length; j++) {
					System.out.print(data[i][j] + " ");
				}
				System.out.println();
			}
		}
	}

	private static void print(char[][] data) {

		if (debug) {
			for (int i = 0; i < data.length; i++) {
				for (int j = 0; j < data[0].length; j++) {
					System.out.print(i + " " + j + ":" + data[i][j] + " ");
				}
				System.out.println();
			}
		}
	}

	private static void print(String[][] data) {

		if (debug) {
			for (int i = 0; i < data.length; i++) {
				for (int j = 0; j < data[0].length; j++) {
					System.out.print(i + " " + j + ":" + data[i][j] + " ");
				}
				System.out.println();
			}
		}
	}

	private static void print(double[][] data) {

		if (debug) {
			for (int i = 0; i < data[0].length; i++) {
				for (int j = 0; j < data.length; j++) {
					System.out.print(i + " " + j + ":" + data[i][j] + " ");
				}
				System.out.println();
			}
		}
	}

	public static void inPutData(char[][] c) {
		for (int i = 0; i < c.length; i++) {
			c[i] = sc.nextLine().toCharArray();
		}
	}

}