import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++) {
            arr[i] = in.nextInt();
        }
        int count = 1;
        int max = 1;
        for (int i = 1; i < n; i++) {
            if (Math.abs(arr[i] - arr[i - 1]) <= 1) {
                count++;
            } else {
                count = 1;
            }
            if (count > max) {
                max = count;
            }
        }
        System.out.println(max);
    }
}