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();
        }
        
        int count1 = 0, count2 = 0, result = 2, finalRes = 2;
        for(int i=0; i<n; i++){
            count1 = 0;
            count2 = 0;
            for(int j=0; j<n; j++){
                if(a[i]-a[j] ==-1 || a[i]-a[j] == 0){
                    ++count1;
 //                   System.out.println("count1:"+ count1);
                }
                if(a[i]-a[j] == 1 || a[i]-a[j] == 0){
                    ++count2;
 //                   System.out.println("count2:"+ count2);
                }
            }
            if(count1>count2){
              result=count1;
 //             System.out.println("result is 1:"+ result);
            } 
            else {
                result = count2;
//                System.out.println("result is 2:"+ result);

            }
            if(result>finalRes) finalRes = result;
        }
        System.out.println(finalRes);
    }
}