import java.util.Scanner;

public class Main{
	public static void main(String[] args){
		Scanner in = new Scanner(System.in);
		int h,w;
		
		h=in.nextInt();
		w=in.nextInt();
		
		while(h!=0 || w!=0){
			for(int i=0; i<h; i++){
				for(int j=0; j<w; j++){
					if(i%2 == 0){
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					}else{
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					}
				}
				System.out.println();
			}
			
			System.out.println();
			h = in.nextInt();
			w = in.nextInt();
		}
	}
} import java.util.Scanner; Scanner java.util public class Main{
	public static void main(String[] args){
		Scanner in = new Scanner(System.in);
		int h,w;
		
		h=in.nextInt();
		w=in.nextInt();
		
		while(h!=0 || w!=0){
			for(int i=0; i<h; i++){
				for(int j=0; j<w; j++){
					if(i%2 == 0){
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					}else{
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					}
				}
				System.out.println();
			}
			
			System.out.println();
			h = in.nextInt();
			w = in.nextInt();
		}
	}
} Main public static void main(String[] args){
		Scanner in = new Scanner(System.in);
		int h,w;
		
		h=in.nextInt();
		w=in.nextInt();
		
		while(h!=0 || w!=0){
			for(int i=0; i<h; i++){
				for(int j=0; j<w; j++){
					if(i%2 == 0){
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					}else{
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					}
				}
				System.out.println();
			}
			
			System.out.println();
			h = in.nextInt();
			w = in.nextInt();
		}
	} main {
		Scanner in = new Scanner(System.in);
		int h,w;
		
		h=in.nextInt();
		w=in.nextInt();
		
		while(h!=0 || w!=0){
			for(int i=0; i<h; i++){
				for(int j=0; j<w; j++){
					if(i%2 == 0){
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					}else{
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					}
				}
				System.out.println();
			}
			
			System.out.println();
			h = in.nextInt();
			w = in.nextInt();
		}
	} Scanner in = new Scanner(System.in); in new Scanner(System.in) int h h w; w h=in.nextInt() h in.nextInt() in.nextInt in w=in.nextInt() w in.nextInt() in.nextInt in while(h!=0 || w!=0){
			for(int i=0; i<h; i++){
				for(int j=0; j<w; j++){
					if(i%2 == 0){
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					}else{
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					}
				}
				System.out.println();
			}
			
			System.out.println();
			h = in.nextInt();
			w = in.nextInt();
		} h!=0 || w!=0 h!=0 h 0 w!=0 w 0 {
			for(int i=0; i<h; i++){
				for(int j=0; j<w; j++){
					if(i%2 == 0){
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					}else{
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					}
				}
				System.out.println();
			}
			
			System.out.println();
			h = in.nextInt();
			w = in.nextInt();
		} for(int i=0; i<h; i++){
				for(int j=0; j<w; j++){
					if(i%2 == 0){
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					}else{
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					}
				}
				System.out.println();
			} int i=0; int i=0; i 0 i<h i h i++ i++ i {
				for(int j=0; j<w; j++){
					if(i%2 == 0){
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					}else{
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					}
				}
				System.out.println();
			} {
				for(int j=0; j<w; j++){
					if(i%2 == 0){
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					}else{
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					}
				}
				System.out.println();
			} for(int j=0; j<w; j++){
					if(i%2 == 0){
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					}else{
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					}
				} int j=0; int j=0; j 0 j<w j w j++ j++ j {
					if(i%2 == 0){
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					}else{
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					}
				} {
					if(i%2 == 0){
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					}else{
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					}
				} if(i%2 == 0){
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					}else{
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					} i%2 == 0 i%2 i 2 0 {
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					} if(j%2 == 0){
							System.out.print('#');
						}else{
							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 '#' {
							System.out.print('.');
						} System.out.print('.') System.out.print System.out System System.out '.' {
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					} if(j%2 == 0){
							System.out.print('.');
						}else{
							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 '.' {
							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 = in.nextInt() h in.nextInt() in.nextInt in w = in.nextInt() w in.nextInt() in.nextInt in String[] args args public class Main{
	public static void main(String[] args){
		Scanner in = new Scanner(System.in);
		int h,w;
		
		h=in.nextInt();
		w=in.nextInt();
		
		while(h!=0 || w!=0){
			for(int i=0; i<h; i++){
				for(int j=0; j<w; j++){
					if(i%2 == 0){
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					}else{
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					}
				}
				System.out.println();
			}
			
			System.out.println();
			h = in.nextInt();
			w = in.nextInt();
		}
	}
} public class Main{
	public static void main(String[] args){
		Scanner in = new Scanner(System.in);
		int h,w;
		
		h=in.nextInt();
		w=in.nextInt();
		
		while(h!=0 || w!=0){
			for(int i=0; i<h; i++){
				for(int j=0; j<w; j++){
					if(i%2 == 0){
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					}else{
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					}
				}
				System.out.println();
			}
			
			System.out.println();
			h = in.nextInt();
			w = in.nextInt();
		}
	}
} Main
import java.util.Scanner;

public class Main{
	public static void main(String[] args){
		Scanner in = new Scanner(System.in);
		int h,w;
		
		h=in.nextInt();
		w=in.nextInt();
		
		while(h!=0 || w!=0){
			for(int i=0; i<h; i++){
				for(int j=0; j<w; j++){
					if(i%2 == 0){
						if(j%2 == 0){
							System.out.print('#');
						}else{
							System.out.print('.');
						}
					}else{
						if(j%2 == 0){
							System.out.print('.');
						}else{
							System.out.print('#');
						}
					}
				}
				System.out.println();
			}
			
			System.out.println();
			h = in.nextInt();
			w = in.nextInt();
		}
	}
}