using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
class Solution {

    static void Main(String[] args) {
        int n = Convert.ToInt32(Console.ReadLine());
        string[] a_temp = Console.ReadLine().Split(' ');
        int[] a = Array.ConvertAll(a_temp,Int32.Parse);
        
        var sorted = a.OrderBy(i => i).ToArray();
        
        var result = 1;
        var currentCounter = 1;
        
        var lowVal = sorted[0]; //first value of streak
        var lastValIdx = 0; //start at first item
                
        for(int i=1; i < n; i++) {
            var cur = sorted[i];
            
            //last streak is over, need to start a new one
            if (cur - lowVal > 1) {
                if (cur - sorted[lastValIdx] > 1) {
                    lastValIdx = i;
                    currentCounter = 1;
                    lowVal = cur;
                    continue; //don't let counter below increment
                } else {
                    //new streak is in-progress set counter to difference of last change and reset lowval
                    currentCounter = i - lastValIdx;
                    lowVal = sorted[lastValIdx];
                    lastValIdx = i;
                }
            } else if (cur > sorted[lastValIdx]) {
                //need to increment last val idx but we're still within 2 to streak continues
                lastValIdx = i;
            }
            
            currentCounter++;
            
            if (result < currentCounter) {
                result = currentCounter;
            }
        }
        
        Console.WriteLine(result);
    }
}