import java.util.Scanner;



public class Main {

    public static void gyo1(int w2, int number){
        if ( w2 == 1) {
            for (int a = 0; a < number; a++) {
                System.out.printf("#.");
            }
            System.out.printf("#");
        } else {
            for (int a = 0; a < number; a++) {
                System.out.printf("#.");
            }
        }
        System.out.printf("\n");
    }

    public static void gyo2(int n, int number){
        if ( n == 1) {
            for (int a = 0; a < number ; a++) {
                System.out.printf(".#");
            }
            System.out.printf(".");
        } else {
            for (int a = 0; a < number; a++) {
                System.out.printf(".#");
            }
        }
        System.out.printf("\n");
    }


    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        while(true) {
            int H = input.nextInt();
            int W = input.nextInt();
            if (H == 0 && W == 0) {
                break;
            }
            int w2 = W % 2;
            for (int i = 0; i < H; i = i + 1) {
                if (i % 2 == 0) {
                    gyo1(w2, W / 2);
                    continue;
                }
                gyo2(w2, W / 2);
            }
            // }
            //第一行目の”＃. # .”

        }
    }

}
