import java.util.Scanner;

class Main {

	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);

		int str1 = scan.nextInt();
		int str2 = scan.nextInt();
		
		int i = 0;
		int j = 0;
		
		while(str1 != 0 && str2 != 0){
			for(i = 1; i <= str1; i++){
				for(j = 1; j <= str2; j++){
					if(i%2==1){
						if(j%2==0){
							System.out.print(".");
						}else if(j%2==1){
							System.out.print("#");
						}
					}else if(i%2==0){
						if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
			str1 = scan.nextInt();
			str2 = scan.nextInt();

		}
		
	}
} import java.util.Scanner; Scanner java.util class Main {

	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);

		int str1 = scan.nextInt();
		int str2 = scan.nextInt();
		
		int i = 0;
		int j = 0;
		
		while(str1 != 0 && str2 != 0){
			for(i = 1; i <= str1; i++){
				for(j = 1; j <= str2; j++){
					if(i%2==1){
						if(j%2==0){
							System.out.print(".");
						}else if(j%2==1){
							System.out.print("#");
						}
					}else if(i%2==0){
						if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
			str1 = scan.nextInt();
			str2 = scan.nextInt();

		}
		
	}
} Main public static void main(String[] args){
		Scanner scan = new Scanner(System.in);

		int str1 = scan.nextInt();
		int str2 = scan.nextInt();
		
		int i = 0;
		int j = 0;
		
		while(str1 != 0 && str2 != 0){
			for(i = 1; i <= str1; i++){
				for(j = 1; j <= str2; j++){
					if(i%2==1){
						if(j%2==0){
							System.out.print(".");
						}else if(j%2==1){
							System.out.print("#");
						}
					}else if(i%2==0){
						if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
			str1 = scan.nextInt();
			str2 = scan.nextInt();

		}
		
	} main {
		Scanner scan = new Scanner(System.in);

		int str1 = scan.nextInt();
		int str2 = scan.nextInt();
		
		int i = 0;
		int j = 0;
		
		while(str1 != 0 && str2 != 0){
			for(i = 1; i <= str1; i++){
				for(j = 1; j <= str2; j++){
					if(i%2==1){
						if(j%2==0){
							System.out.print(".");
						}else if(j%2==1){
							System.out.print("#");
						}
					}else if(i%2==0){
						if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
			str1 = scan.nextInt();
			str2 = scan.nextInt();

		}
		
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int str1 = scan.nextInt(); str1 scan.nextInt() scan.nextInt scan int str2 = scan.nextInt(); str2 scan.nextInt() scan.nextInt scan int i = 0; i 0 int j = 0; j 0 while(str1 != 0 && str2 != 0){
			for(i = 1; i <= str1; i++){
				for(j = 1; j <= str2; j++){
					if(i%2==1){
						if(j%2==0){
							System.out.print(".");
						}else if(j%2==1){
							System.out.print("#");
						}
					}else if(i%2==0){
						if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
			str1 = scan.nextInt();
			str2 = scan.nextInt();

		} str1 != 0 && str2 != 0 str1 != 0 str1 0 str2 != 0 str2 0 {
			for(i = 1; i <= str1; i++){
				for(j = 1; j <= str2; j++){
					if(i%2==1){
						if(j%2==0){
							System.out.print(".");
						}else if(j%2==1){
							System.out.print("#");
						}
					}else if(i%2==0){
						if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
			str1 = scan.nextInt();
			str2 = scan.nextInt();

		} for(i = 1; i <= str1; i++){
				for(j = 1; j <= str2; j++){
					if(i%2==1){
						if(j%2==0){
							System.out.print(".");
						}else if(j%2==1){
							System.out.print("#");
						}
					}else if(i%2==0){
						if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						}
					}
				}
				System.out.println();
			} i = 1; i = 1 i 1 i <= str1 i str1 i++ i++ i {
				for(j = 1; j <= str2; j++){
					if(i%2==1){
						if(j%2==0){
							System.out.print(".");
						}else if(j%2==1){
							System.out.print("#");
						}
					}else if(i%2==0){
						if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						}
					}
				}
				System.out.println();
			} {
				for(j = 1; j <= str2; j++){
					if(i%2==1){
						if(j%2==0){
							System.out.print(".");
						}else if(j%2==1){
							System.out.print("#");
						}
					}else if(i%2==0){
						if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						}
					}
				}
				System.out.println();
			} for(j = 1; j <= str2; j++){
					if(i%2==1){
						if(j%2==0){
							System.out.print(".");
						}else if(j%2==1){
							System.out.print("#");
						}
					}else if(i%2==0){
						if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						}
					}
				} j = 1; j = 1 j 1 j <= str2 j str2 j++ j++ j {
					if(i%2==1){
						if(j%2==0){
							System.out.print(".");
						}else if(j%2==1){
							System.out.print("#");
						}
					}else if(i%2==0){
						if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						}
					}
				} {
					if(i%2==1){
						if(j%2==0){
							System.out.print(".");
						}else if(j%2==1){
							System.out.print("#");
						}
					}else if(i%2==0){
						if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						}
					}
				} if(i%2==1){
						if(j%2==0){
							System.out.print(".");
						}else if(j%2==1){
							System.out.print("#");
						}
					}else if(i%2==0){
						if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						}
					} i%2==1 i%2 i 2 1 {
						if(j%2==0){
							System.out.print(".");
						}else if(j%2==1){
							System.out.print("#");
						}
					} if(j%2==0){
							System.out.print(".");
						}else if(j%2==1){
							System.out.print("#");
						} j%2==0 j%2 j 2 0 {
							System.out.print(".");
						} System.out.print(".") System.out.print System.out System System.out "." if(j%2==1){
							System.out.print("#");
						} j%2==1 j%2 j 2 1 {
							System.out.print("#");
						} System.out.print("#") System.out.print System.out System System.out "#" if(i%2==0){
						if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						}
					} i%2==0 i%2 i 2 0 {
						if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						}
					} if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						} j%2==0 j%2 j 2 0 {
							System.out.print("#");
						} System.out.print("#") System.out.print System.out System System.out "#" if(j%2==1){
							System.out.print(".");
						} j%2==1 j%2 j 2 1 {
							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 str1 = scan.nextInt() str1 scan.nextInt() scan.nextInt scan str2 = scan.nextInt() str2 scan.nextInt() scan.nextInt scan String[] args args
import java.util.Scanner;

class Main {

	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);

		int str1 = scan.nextInt();
		int str2 = scan.nextInt();
		
		int i = 0;
		int j = 0;
		
		while(str1 != 0 && str2 != 0){
			for(i = 1; i <= str1; i++){
				for(j = 1; j <= str2; j++){
					if(i%2==1){
						if(j%2==0){
							System.out.print(".");
						}else if(j%2==1){
							System.out.print("#");
						}
					}else if(i%2==0){
						if(j%2==0){
							System.out.print("#");
						}else if(j%2==1){
							System.out.print(".");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
			str1 = scan.nextInt();
			str2 = scan.nextInt();

		}
		
	}
}