import java.util.Scanner;
public class Main {
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		for(int a = 1;a>0;a++){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			for(int b = 0;b<H;b++){
				for(int c =0;c<W;c++){
					if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		for(int a = 1;a>0;a++){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			for(int b = 0;b<H;b++){
				for(int c =0;c<W;c++){
					if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	}
} Main public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		for(int a = 1;a>0;a++){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			for(int b = 0;b<H;b++){
				for(int c =0;c<W;c++){
					if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	} main {
		Scanner scan = new Scanner(System.in);
		for(int a = 1;a>0;a++){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			for(int b = 0;b<H;b++){
				for(int c =0;c<W;c++){
					if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) for(int a = 1;a>0;a++){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			for(int b = 0;b<H;b++){
				for(int c =0;c<W;c++){
					if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		} int a = 1; int a = 1; a 1 a>0 a 0 a++ a++ a {
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			for(int b = 0;b<H;b++){
				for(int c =0;c<W;c++){
					if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		} {
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			for(int b = 0;b<H;b++){
				for(int c =0;c<W;c++){
					if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		} 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;
			} break; for(int b = 0;b<H;b++){
				for(int c =0;c<W;c++){
					if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			} int b = 0; int b = 0; b 0 b<H b H b++ b++ b {
				for(int c =0;c<W;c++){
					if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			} {
				for(int c =0;c<W;c++){
					if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			} for(int c =0;c<W;c++){
					if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				} int c =0; int c =0; c 0 c<W c W c++ c++ c {
					if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				} {
					if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				} if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					} b%2 == 0 b%2 b 2 0 {
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					} if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						} c%2 == 0 c%2 c 2 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 "." {
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					} if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						} c%2 == 0 c%2 c 2 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 "" String[] args args public class Main {
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		for(int a = 1;a>0;a++){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			for(int b = 0;b<H;b++){
				for(int c =0;c<W;c++){
					if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	}
} public class Main {
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		for(int a = 1;a>0;a++){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			for(int b = 0;b<H;b++){
				for(int c =0;c<W;c++){
					if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	}
} Main
import java.util.Scanner;
public class Main {
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		for(int a = 1;a>0;a++){
			int H = scan.nextInt();
			int W = scan.nextInt();
			if(H == 0 && W == 0){
				break;
			}
			for(int b = 0;b<H;b++){
				for(int c =0;c<W;c++){
					if(b%2 == 0){
						if(c%2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(c%2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	}
}