using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace hrHourRank44
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.ReadLine();
            var nums = Console.ReadLine().Split().Select(int.Parse).OrderBy(x => x).ToArray();
            var maxCount = 0;
            for (int i = 0; i < nums.Length; i++)
            {
                var curVal = nums[i];
                var curLowerCount = nums.Where(x => x == curVal || x == curVal - 1).Count();
                var curUpperCount = nums.Where(x => x == curVal || x == curVal + 1).Count();
                if (curLowerCount > maxCount)
                {
                    maxCount = curLowerCount;
                }
                if (curUpperCount > maxCount)
                {
                    maxCount = curUpperCount;
                }
            }
            Console.WriteLine(maxCount);
        }
    }
}