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 C# (Mono 4.6.2.0) (judge verdict: Time Limit Exceeded)

using System;
using System.Linq;
class Program
{
    static void Main(string[] args)
    {
        long n = Read.Long();
        long[] a = Read.longs();
        long max = a.Max();
        long min = a.Min();
        long kumiawase_kari = 0;
        long kumi = 0;
        for (long i = min; i <= max; i++)
        {
            for (long k = 0; k < a.Length; k++)
            {
                if (Math.Abs(a[k] - i) <= 1)
                {
                    kumiawase_kari++;
                }
            }
            kumi = Math.Max(kumi, kumiawase_kari);
            kumiawase_kari = 0;

        }
        Console.WriteLine(kumi);
        Console.ReadLine();
    }
}
    public static class Read
{
    public static long Long()
    {
        return long.Parse(Console.ReadLine());
    }
    public static long[] longs()
    {
        return Console.ReadLine().Split().Select(long.Parse).ToArray();
    }
 }