import java.util.Scanner;

class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		for(;;){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				scan.close();
				break;
			}

			for(int i = 0; i < H; i++){ //縦の列の繰り返し
				if(i%2 == 0){
					for(int s=0; s<W; s++){ //偶数列の横の行の繰り返し
						if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print(".");
					}
				}else{
					for(int t=0; t<W; t++){ //奇数列の横の行の繰り返し
						if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#");
					}
				}
				System.out.print("\n");
			}
			System.out.print("\n");
		}
	}
} import java.util.Scanner; Scanner java.util class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		for(;;){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				scan.close();
				break;
			}

			for(int i = 0; i < H; i++){ //縦の列の繰り返し
				if(i%2 == 0){
					for(int s=0; s<W; s++){ //偶数列の横の行の繰り返し
						if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print(".");
					}
				}else{
					for(int t=0; t<W; t++){ //奇数列の横の行の繰り返し
						if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#");
					}
				}
				System.out.print("\n");
			}
			System.out.print("\n");
		}
	}
} Main public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		for(;;){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				scan.close();
				break;
			}

			for(int i = 0; i < H; i++){ //縦の列の繰り返し
				if(i%2 == 0){
					for(int s=0; s<W; s++){ //偶数列の横の行の繰り返し
						if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print(".");
					}
				}else{
					for(int t=0; t<W; t++){ //奇数列の横の行の繰り返し
						if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#");
					}
				}
				System.out.print("\n");
			}
			System.out.print("\n");
		}
	} main {

		Scanner scan = new Scanner(System.in);

		for(;;){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				scan.close();
				break;
			}

			for(int i = 0; i < H; i++){ //縦の列の繰り返し
				if(i%2 == 0){
					for(int s=0; s<W; s++){ //偶数列の横の行の繰り返し
						if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print(".");
					}
				}else{
					for(int t=0; t<W; t++){ //奇数列の横の行の繰り返し
						if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#");
					}
				}
				System.out.print("\n");
			}
			System.out.print("\n");
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) for(;;){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				scan.close();
				break;
			}

			for(int i = 0; i < H; i++){ //縦の列の繰り返し
				if(i%2 == 0){
					for(int s=0; s<W; s++){ //偶数列の横の行の繰り返し
						if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print(".");
					}
				}else{
					for(int t=0; t<W; t++){ //奇数列の横の行の繰り返し
						if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#");
					}
				}
				System.out.print("\n");
			}
			System.out.print("\n");
		} ; {
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				scan.close();
				break;
			}

			for(int i = 0; i < H; i++){ //縦の列の繰り返し
				if(i%2 == 0){
					for(int s=0; s<W; s++){ //偶数列の横の行の繰り返し
						if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print(".");
					}
				}else{
					for(int t=0; t<W; t++){ //奇数列の横の行の繰り返し
						if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#");
					}
				}
				System.out.print("\n");
			}
			System.out.print("\n");
		} {
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				scan.close();
				break;
			}

			for(int i = 0; i < H; i++){ //縦の列の繰り返し
				if(i%2 == 0){
					for(int s=0; s<W; s++){ //偶数列の横の行の繰り返し
						if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print(".");
					}
				}else{
					for(int t=0; t<W; t++){ //奇数列の横の行の繰り返し
						if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#");
					}
				}
				System.out.print("\n");
			}
			System.out.print("\n");
		} int H = scan.nextInt(); H scan.nextInt() scan.nextInt scan int W = scan.nextInt(); W scan.nextInt() scan.nextInt scan if(H == 0 && W == 0){
				scan.close();
				break;
			} H == 0 && W == 0 H == 0 H 0 W == 0 W 0 {
				scan.close();
				break;
			} scan.close() scan.close scan break; for(int i = 0; i < H; i++){ //縦の列の繰り返し
				if(i%2 == 0){
					for(int s=0; s<W; s++){ //偶数列の横の行の繰り返し
						if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print(".");
					}
				}else{
					for(int t=0; t<W; t++){ //奇数列の横の行の繰り返し
						if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#");
					}
				}
				System.out.print("\n");
			} int i = 0; int i = 0; i 0 i < H i H i++ i++ i { //縦の列の繰り返し
				if(i%2 == 0){
					for(int s=0; s<W; s++){ //偶数列の横の行の繰り返し
						if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print(".");
					}
				}else{
					for(int t=0; t<W; t++){ //奇数列の横の行の繰り返し
						if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#");
					}
				}
				System.out.print("\n");
			} { //縦の列の繰り返し
				if(i%2 == 0){
					for(int s=0; s<W; s++){ //偶数列の横の行の繰り返し
						if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print(".");
					}
				}else{
					for(int t=0; t<W; t++){ //奇数列の横の行の繰り返し
						if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#");
					}
				}
				System.out.print("\n");
			} if(i%2 == 0){
					for(int s=0; s<W; s++){ //偶数列の横の行の繰り返し
						if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print(".");
					}
				}else{
					for(int t=0; t<W; t++){ //奇数列の横の行の繰り返し
						if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#");
					}
				} i%2 == 0 i%2 i 2 0 {
					for(int s=0; s<W; s++){ //偶数列の横の行の繰り返し
						if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print(".");
					}
				} for(int s=0; s<W; s++){ //偶数列の横の行の繰り返し
						if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print(".");
					} int s=0; int s=0; s 0 s<W s W s++ s++ s { //偶数列の横の行の繰り返し
						if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print(".");
					} { //偶数列の横の行の繰り返し
						if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print(".");
					} if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print("."); s%2 == 0 s%2 s 2 0 System.out.print("#") System.out.print System.out System System.out "#" System.out.print(".") System.out.print System.out System System.out "." {
					for(int t=0; t<W; t++){ //奇数列の横の行の繰り返し
						if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#");
					}
				} for(int t=0; t<W; t++){ //奇数列の横の行の繰り返し
						if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#");
					} int t=0; int t=0; t 0 t<W t W t++ t++ t { //奇数列の横の行の繰り返し
						if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#");
					} { //奇数列の横の行の繰り返し
						if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#");
					} if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#"); t%2 == 0 t%2 t 2 0 System.out.print(".") System.out.print System.out System System.out "." System.out.print("#") System.out.print System.out System System.out "#" System.out.print("\n") System.out.print System.out System System.out "\n" System.out.print("\n") System.out.print System.out System System.out "\n" String[] args args
import java.util.Scanner;

class Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		for(;;){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				scan.close();
				break;
			}

			for(int i = 0; i < H; i++){ //縦の列の繰り返し
				if(i%2 == 0){
					for(int s=0; s<W; s++){ //偶数列の横の行の繰り返し
						if(s%2 == 0)
							System.out.print("#");
						else
							System.out.print(".");
					}
				}else{
					for(int t=0; t<W; t++){ //奇数列の横の行の繰り返し
						if(t%2 == 0)
							System.out.print(".");
						else
							System.out.print("#");
					}
				}
				System.out.print("\n");
			}
			System.out.print("\n");
		}
	}
}