import java.util.Scanner;

public class stripedTowel300815 {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int size = Integer.parseInt(scan.nextLine());
        int width = size;
        int height = size + size / 2;
        for (int i = 0; i < height; i++){
            for (int j = 0; j < width; j++){
                if ((j + i) % 3 == 0){
                    System.out.print("#");
                }else{
                    System.out.print(".");
                }
            }
            System.out.println();
        }
    }
}