import java.util.Scanner;
class Main {
	int H = 0,W = 0,i,j,a,b;
	public void ch() {
		Scanner sc = new Scanner(System.in);
		H = sc.nextInt();
		W = sc.nextInt();
		while(H != 0 || W != 0) {
			for(i = 1; i <= H;i++) {
				for(j = 1; j <= W;j++) {
					a = i % 2;
					b = j % 2;
					if(b == 1) {
						if(a == 1) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else if(a == 0) {
						System.out.print("#");
					} else {
						System.out.print(".");
					}
				}
			System.out.println();
			}
			H = sc.nextInt();
			W = sc.nextInt();
		}
	}
	public static void main(String[] args) {
		new Main().ch();
	}
}