import java.util.Scanner;

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

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

