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();
        }
        Set<Long> numbers = new HashSet<>();
        for (int x : a) {
            long count1 = Arrays.stream(a).filter(num -> (num == x || num == (x - 1))).count();
            long count2 = Arrays.stream(a).filter(num -> (num == x || num == (x + 1))).count();
            numbers.add(Math.max(count1, count2));
        }
        Optional<Long> max = numbers.stream().max(Comparator.naturalOrder());
        if (max.isPresent())
            System.out.println(max.get());
    }
}