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];
        //ArrayList<Integer> al = new ArrayList<>();
        //int lowest = Integer.MAX_VALUE;
        //int highest = Integer.MIN_VALUE;
        for(int a_i=0; a_i < n; a_i++){
            a[a_i] = in.nextInt();
        }
        int largest = 1;
        for(int i = 0; i < a.length; i++){
            int counter = 0;
            int[] al = new int[2];
            for(int ix = 0; ix < a.length; ix++){
                //if lower, check a[ix] if it's higher than a[i]
                //reset the current if a[i] difference from curr is greater than 0 
                if(Math.abs(a[ix] - a[i]) <= 1){
                    //keep counter of numbers larger and smaller
                    if(a[ix] <= a[i]){
                        al[0]++;
                    } else {
                        al[1]++;
                    }
                }
            }
            counter = Math.max(al[0], al[1]);
            largest = Math.max(largest, counter);
        }
        System.out.println(largest);
    }
}