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-i;j++)
                {
                if(a[j]>a[j+1])
                    {
                    int t=a[j];
                    a[j]=a[j+1];
                    a[j+1]=t;
                }
            }
        }
       
        
        int big=0;
    for(int i=0;i<n;i++)
        {
        for(int j=n-1;j>=i;j--)
            {
            if((a[j]-a[i])<=1)
                {
                if((j-i+1)>big)
                big=j-i+1;
                break;
                    
            }
        }
    }
        System.out.println(big); 
    }
}