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

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[] a = new int[n];
        for(int a_i=0; a_i < n; a_i++)
        {
            a[a_i] = in.nextInt();
        }
        
        for(int i=0;i<n;i++)
            {
            for(int j=0;j<(n-1);j++)
               { if(a[j]>a[j+1])
                    {
                int temp=a[j];
                a[j]=a[j+1];
                a[j+1]=temp;
                    
            }
               }
            
        }
        int count=0;
        int curr=0;
        int next=1;
        int max=-9999;
        while(next<n)
            {
            if(a[next]-a[curr]<=1)
                {
                if(next-curr>max)
                    max=next-curr;
                
                next++;
            }
            else
                {
                curr++;
                next=curr+1;
            }
        }
        System.out.println(max+1);
        
    }
}