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