import java.util.*;

public class Solution {

    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int size = new Integer(sc.nextLine());
        int[] arr = new int[size];
        String line = sc.nextLine();
        String[] el = line.split(" ");
        for (int i = 0; i < size; i++) {
            arr[i] = new Integer(el[i]);
        }
        minDifference(arr);
    }
    
    private static void minDifference(int[] arr) throws Exception {
        int maxLength = 0;
        for (int i = 0; i < arr.length; i++) {
            int count1 = 1, count2 = 1;
            for (int j = 0; j < arr.length; j++) {
                if (i == j) continue;
                if (arr[i]-arr[j] == 0 || arr[i]-arr[j] == 1)
                    count1++;
                if (arr[i]-arr[j] == 0 || arr[i]-arr[j] == -1)
                    count2++;
            }
            int maxCount = Math.max(count1, count2);
            if (maxCount > maxLength)
                maxLength = maxCount;
        }
        System.out.println(maxLength);
    }
    
}