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 max = 0;
        for(int a_i=0; a_i < n; a_i++){
            int sumup = 0;
            int sumdown = 0;
            for(int a_j=0; a_j < n; a_j++){
              if ((a[a_i]-a[a_j]) == 0 || (a[a_i]-a[a_j]) == 1)sumdown++;
              if ((a[a_i]-a[a_j]) == 0 || (a[a_i]-a[a_j]) == -1)sumup++;
            }
        if (sumdown>max)max=sumdown;
        if (sumup>max)max=sumup;
        }
        System.out.println(max);
    }
}