import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		StringBuilder output = new StringBuilder();
		
		while(true) {
			int H = scan.nextInt();
			int W = scan.nextInt();
			
			if (H == 0 && W == 0)
				break;
			
				for (int i = 0; i < H/2; i++) {
						for (int j = 0; j < W/2; j++) {
							output.append("#").append(".");
						}
						if (W%2 == 1) {
							output.append("#");
						}
						output.append('\n');
						for (int j = 0; j < W/2; j++) {
							output.append(".").append("#");
						}
						if (W%2 == 1) {
							output.append(".");
						}
						output.append('\n');
				}
			if (H%2 == 1) {
				for (int l = 0; l < W/2; l++) {
					output.append("#").append(".");
				}
				if (W%2 == 1) {
					output.append("#");
				}
				output.append('\n');
			}
			output.append('\n');
		}
		System.out.print(output);
	}

} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		StringBuilder output = new StringBuilder();
		
		while(true) {
			int H = scan.nextInt();
			int W = scan.nextInt();
			
			if (H == 0 && W == 0)
				break;
			
				for (int i = 0; i < H/2; i++) {
						for (int j = 0; j < W/2; j++) {
							output.append("#").append(".");
						}
						if (W%2 == 1) {
							output.append("#");
						}
						output.append('\n');
						for (int j = 0; j < W/2; j++) {
							output.append(".").append("#");
						}
						if (W%2 == 1) {
							output.append(".");
						}
						output.append('\n');
				}
			if (H%2 == 1) {
				for (int l = 0; l < W/2; l++) {
					output.append("#").append(".");
				}
				if (W%2 == 1) {
					output.append("#");
				}
				output.append('\n');
			}
			output.append('\n');
		}
		System.out.print(output);
	}

} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		StringBuilder output = new StringBuilder();
		
		while(true) {
			int H = scan.nextInt();
			int W = scan.nextInt();
			
			if (H == 0 && W == 0)
				break;
			
				for (int i = 0; i < H/2; i++) {
						for (int j = 0; j < W/2; j++) {
							output.append("#").append(".");
						}
						if (W%2 == 1) {
							output.append("#");
						}
						output.append('\n');
						for (int j = 0; j < W/2; j++) {
							output.append(".").append("#");
						}
						if (W%2 == 1) {
							output.append(".");
						}
						output.append('\n');
				}
			if (H%2 == 1) {
				for (int l = 0; l < W/2; l++) {
					output.append("#").append(".");
				}
				if (W%2 == 1) {
					output.append("#");
				}
				output.append('\n');
			}
			output.append('\n');
		}
		System.out.print(output);
	} main {
		Scanner scan = new Scanner(System.in);
		StringBuilder output = new StringBuilder();
		
		while(true) {
			int H = scan.nextInt();
			int W = scan.nextInt();
			
			if (H == 0 && W == 0)
				break;
			
				for (int i = 0; i < H/2; i++) {
						for (int j = 0; j < W/2; j++) {
							output.append("#").append(".");
						}
						if (W%2 == 1) {
							output.append("#");
						}
						output.append('\n');
						for (int j = 0; j < W/2; j++) {
							output.append(".").append("#");
						}
						if (W%2 == 1) {
							output.append(".");
						}
						output.append('\n');
				}
			if (H%2 == 1) {
				for (int l = 0; l < W/2; l++) {
					output.append("#").append(".");
				}
				if (W%2 == 1) {
					output.append("#");
				}
				output.append('\n');
			}
			output.append('\n');
		}
		System.out.print(output);
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) StringBuilder output = new StringBuilder(); output new StringBuilder() while(true) {
			int H = scan.nextInt();
			int W = scan.nextInt();
			
			if (H == 0 && W == 0)
				break;
			
				for (int i = 0; i < H/2; i++) {
						for (int j = 0; j < W/2; j++) {
							output.append("#").append(".");
						}
						if (W%2 == 1) {
							output.append("#");
						}
						output.append('\n');
						for (int j = 0; j < W/2; j++) {
							output.append(".").append("#");
						}
						if (W%2 == 1) {
							output.append(".");
						}
						output.append('\n');
				}
			if (H%2 == 1) {
				for (int l = 0; l < W/2; l++) {
					output.append("#").append(".");
				}
				if (W%2 == 1) {
					output.append("#");
				}
				output.append('\n');
			}
			output.append('\n');
		} true {
			int H = scan.nextInt();
			int W = scan.nextInt();
			
			if (H == 0 && W == 0)
				break;
			
				for (int i = 0; i < H/2; i++) {
						for (int j = 0; j < W/2; j++) {
							output.append("#").append(".");
						}
						if (W%2 == 1) {
							output.append("#");
						}
						output.append('\n');
						for (int j = 0; j < W/2; j++) {
							output.append(".").append("#");
						}
						if (W%2 == 1) {
							output.append(".");
						}
						output.append('\n');
				}
			if (H%2 == 1) {
				for (int l = 0; l < W/2; l++) {
					output.append("#").append(".");
				}
				if (W%2 == 1) {
					output.append("#");
				}
				output.append('\n');
			}
			output.append('\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)
				break; H == 0 && W == 0 H == 0 H 0 W == 0 W 0 break; for (int i = 0; i < H/2; i++) {
						for (int j = 0; j < W/2; j++) {
							output.append("#").append(".");
						}
						if (W%2 == 1) {
							output.append("#");
						}
						output.append('\n');
						for (int j = 0; j < W/2; j++) {
							output.append(".").append("#");
						}
						if (W%2 == 1) {
							output.append(".");
						}
						output.append('\n');
				} int i = 0; int i = 0; i 0 i < H/2 i H/2 H 2 i++ i++ i {
						for (int j = 0; j < W/2; j++) {
							output.append("#").append(".");
						}
						if (W%2 == 1) {
							output.append("#");
						}
						output.append('\n');
						for (int j = 0; j < W/2; j++) {
							output.append(".").append("#");
						}
						if (W%2 == 1) {
							output.append(".");
						}
						output.append('\n');
				} {
						for (int j = 0; j < W/2; j++) {
							output.append("#").append(".");
						}
						if (W%2 == 1) {
							output.append("#");
						}
						output.append('\n');
						for (int j = 0; j < W/2; j++) {
							output.append(".").append("#");
						}
						if (W%2 == 1) {
							output.append(".");
						}
						output.append('\n');
				} for (int j = 0; j < W/2; j++) {
							output.append("#").append(".");
						} int j = 0; int j = 0; j 0 j < W/2 j W/2 W 2 j++ j++ j {
							output.append("#").append(".");
						} {
							output.append("#").append(".");
						} output.append("#").append(".") output.append("#").append output.append("#") output.append output "#" "." if (W%2 == 1) {
							output.append("#");
						} W%2 == 1 W%2 W 2 1 {
							output.append("#");
						} output.append("#") output.append output "#" output.append('\n') output.append output '\n' for (int j = 0; j < W/2; j++) {
							output.append(".").append("#");
						} int j = 0; int j = 0; j 0 j < W/2 j W/2 W 2 j++ j++ j {
							output.append(".").append("#");
						} {
							output.append(".").append("#");
						} output.append(".").append("#") output.append(".").append output.append(".") output.append output "." "#" if (W%2 == 1) {
							output.append(".");
						} W%2 == 1 W%2 W 2 1 {
							output.append(".");
						} output.append(".") output.append output "." output.append('\n') output.append output '\n' if (H%2 == 1) {
				for (int l = 0; l < W/2; l++) {
					output.append("#").append(".");
				}
				if (W%2 == 1) {
					output.append("#");
				}
				output.append('\n');
			} H%2 == 1 H%2 H 2 1 {
				for (int l = 0; l < W/2; l++) {
					output.append("#").append(".");
				}
				if (W%2 == 1) {
					output.append("#");
				}
				output.append('\n');
			} for (int l = 0; l < W/2; l++) {
					output.append("#").append(".");
				} int l = 0; int l = 0; l 0 l < W/2 l W/2 W 2 l++ l++ l {
					output.append("#").append(".");
				} {
					output.append("#").append(".");
				} output.append("#").append(".") output.append("#").append output.append("#") output.append output "#" "." if (W%2 == 1) {
					output.append("#");
				} W%2 == 1 W%2 W 2 1 {
					output.append("#");
				} output.append("#") output.append output "#" output.append('\n') output.append output '\n' output.append('\n') output.append output '\n' System.out.print(output) System.out.print System.out System System.out output String[] args args public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		StringBuilder output = new StringBuilder();
		
		while(true) {
			int H = scan.nextInt();
			int W = scan.nextInt();
			
			if (H == 0 && W == 0)
				break;
			
				for (int i = 0; i < H/2; i++) {
						for (int j = 0; j < W/2; j++) {
							output.append("#").append(".");
						}
						if (W%2 == 1) {
							output.append("#");
						}
						output.append('\n');
						for (int j = 0; j < W/2; j++) {
							output.append(".").append("#");
						}
						if (W%2 == 1) {
							output.append(".");
						}
						output.append('\n');
				}
			if (H%2 == 1) {
				for (int l = 0; l < W/2; l++) {
					output.append("#").append(".");
				}
				if (W%2 == 1) {
					output.append("#");
				}
				output.append('\n');
			}
			output.append('\n');
		}
		System.out.print(output);
	}

} public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		StringBuilder output = new StringBuilder();
		
		while(true) {
			int H = scan.nextInt();
			int W = scan.nextInt();
			
			if (H == 0 && W == 0)
				break;
			
				for (int i = 0; i < H/2; i++) {
						for (int j = 0; j < W/2; j++) {
							output.append("#").append(".");
						}
						if (W%2 == 1) {
							output.append("#");
						}
						output.append('\n');
						for (int j = 0; j < W/2; j++) {
							output.append(".").append("#");
						}
						if (W%2 == 1) {
							output.append(".");
						}
						output.append('\n');
				}
			if (H%2 == 1) {
				for (int l = 0; l < W/2; l++) {
					output.append("#").append(".");
				}
				if (W%2 == 1) {
					output.append("#");
				}
				output.append('\n');
			}
			output.append('\n');
		}
		System.out.print(output);
	}

} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		StringBuilder output = new StringBuilder();
		
		while(true) {
			int H = scan.nextInt();
			int W = scan.nextInt();
			
			if (H == 0 && W == 0)
				break;
			
				for (int i = 0; i < H/2; i++) {
						for (int j = 0; j < W/2; j++) {
							output.append("#").append(".");
						}
						if (W%2 == 1) {
							output.append("#");
						}
						output.append('\n');
						for (int j = 0; j < W/2; j++) {
							output.append(".").append("#");
						}
						if (W%2 == 1) {
							output.append(".");
						}
						output.append('\n');
				}
			if (H%2 == 1) {
				for (int l = 0; l < W/2; l++) {
					output.append("#").append(".");
				}
				if (W%2 == 1) {
					output.append("#");
				}
				output.append('\n');
			}
			output.append('\n');
		}
		System.out.print(output);
	}

}