import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		for(;;){
			String s=br.readLine();
		    String[] st=s.split(" ");
			int a=Integer.parseInt(st[0]);
			int b=Integer.parseInt(st[1]);
			if(a==0&&b==0)break;
			for(int i=1;i<=a;i++){int m=0;
			
				if(i%2==1){System.out.print("#");m++;}
				for(int l=1;l<=b-m;l++){
					if(l%2==1)System.out.print(".");
					else System.out.print("#");					
				}
			 System.out.println();
			}System.out.println();
		}
		

	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		for(;;){
			String s=br.readLine();
		    String[] st=s.split(" ");
			int a=Integer.parseInt(st[0]);
			int b=Integer.parseInt(st[1]);
			if(a==0&&b==0)break;
			for(int i=1;i<=a;i++){int m=0;
			
				if(i%2==1){System.out.print("#");m++;}
				for(int l=1;l<=b-m;l++){
					if(l%2==1)System.out.print(".");
					else System.out.print("#");					
				}
			 System.out.println();
			}System.out.println();
		}
		

	}
} Main public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		for(;;){
			String s=br.readLine();
		    String[] st=s.split(" ");
			int a=Integer.parseInt(st[0]);
			int b=Integer.parseInt(st[1]);
			if(a==0&&b==0)break;
			for(int i=1;i<=a;i++){int m=0;
			
				if(i%2==1){System.out.print("#");m++;}
				for(int l=1;l<=b-m;l++){
					if(l%2==1)System.out.print(".");
					else System.out.print("#");					
				}
			 System.out.println();
			}System.out.println();
		}
		

	} main {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		for(;;){
			String s=br.readLine();
		    String[] st=s.split(" ");
			int a=Integer.parseInt(st[0]);
			int b=Integer.parseInt(st[1]);
			if(a==0&&b==0)break;
			for(int i=1;i<=a;i++){int m=0;
			
				if(i%2==1){System.out.print("#");m++;}
				for(int l=1;l<=b-m;l++){
					if(l%2==1)System.out.print(".");
					else System.out.print("#");					
				}
			 System.out.println();
			}System.out.println();
		}
		

	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) for(;;){
			String s=br.readLine();
		    String[] st=s.split(" ");
			int a=Integer.parseInt(st[0]);
			int b=Integer.parseInt(st[1]);
			if(a==0&&b==0)break;
			for(int i=1;i<=a;i++){int m=0;
			
				if(i%2==1){System.out.print("#");m++;}
				for(int l=1;l<=b-m;l++){
					if(l%2==1)System.out.print(".");
					else System.out.print("#");					
				}
			 System.out.println();
			}System.out.println();
		} ; {
			String s=br.readLine();
		    String[] st=s.split(" ");
			int a=Integer.parseInt(st[0]);
			int b=Integer.parseInt(st[1]);
			if(a==0&&b==0)break;
			for(int i=1;i<=a;i++){int m=0;
			
				if(i%2==1){System.out.print("#");m++;}
				for(int l=1;l<=b-m;l++){
					if(l%2==1)System.out.print(".");
					else System.out.print("#");					
				}
			 System.out.println();
			}System.out.println();
		} {
			String s=br.readLine();
		    String[] st=s.split(" ");
			int a=Integer.parseInt(st[0]);
			int b=Integer.parseInt(st[1]);
			if(a==0&&b==0)break;
			for(int i=1;i<=a;i++){int m=0;
			
				if(i%2==1){System.out.print("#");m++;}
				for(int l=1;l<=b-m;l++){
					if(l%2==1)System.out.print(".");
					else System.out.print("#");					
				}
			 System.out.println();
			}System.out.println();
		} String s=br.readLine(); s br.readLine() br.readLine br String[] st=s.split(" "); st s.split(" ") s.split s " " int a=Integer.parseInt(st[0]); a Integer.parseInt(st[0]) Integer.parseInt Integer st[0] st 0 int b=Integer.parseInt(st[1]); b Integer.parseInt(st[1]) Integer.parseInt Integer st[1] st 1 if(a==0&&b==0)break; a==0&&b==0 a==0 a 0 b==0 b 0 break; for(int i=1;i<=a;i++){int m=0;
			
				if(i%2==1){System.out.print("#");m++;}
				for(int l=1;l<=b-m;l++){
					if(l%2==1)System.out.print(".");
					else System.out.print("#");					
				}
			 System.out.println();
			} int i=1; int i=1; i 1 i<=a i a i++ i++ i {int m=0;
			
				if(i%2==1){System.out.print("#");m++;}
				for(int l=1;l<=b-m;l++){
					if(l%2==1)System.out.print(".");
					else System.out.print("#");					
				}
			 System.out.println();
			} {int m=0;
			
				if(i%2==1){System.out.print("#");m++;}
				for(int l=1;l<=b-m;l++){
					if(l%2==1)System.out.print(".");
					else System.out.print("#");					
				}
			 System.out.println();
			} int m=0; m 0 if(i%2==1){System.out.print("#");m++;} i%2==1 i%2 i 2 1 {System.out.print("#");m++;} System.out.print("#") System.out.print System.out System System.out "#" m++ m for(int l=1;l<=b-m;l++){
					if(l%2==1)System.out.print(".");
					else System.out.print("#");					
				} int l=1; int l=1; l 1 l<=b-m l b-m b m l++ l++ l {
					if(l%2==1)System.out.print(".");
					else System.out.print("#");					
				} {
					if(l%2==1)System.out.print(".");
					else System.out.print("#");					
				} if(l%2==1)System.out.print(".");
					else System.out.print("#"); l%2==1 l%2 l 2 1 System.out.print(".") System.out.print System.out System System.out "." 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) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		for(;;){
			String s=br.readLine();
		    String[] st=s.split(" ");
			int a=Integer.parseInt(st[0]);
			int b=Integer.parseInt(st[1]);
			if(a==0&&b==0)break;
			for(int i=1;i<=a;i++){int m=0;
			
				if(i%2==1){System.out.print("#");m++;}
				for(int l=1;l<=b-m;l++){
					if(l%2==1)System.out.print(".");
					else System.out.print("#");					
				}
			 System.out.println();
			}System.out.println();
		}
		

	}
} public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		for(;;){
			String s=br.readLine();
		    String[] st=s.split(" ");
			int a=Integer.parseInt(st[0]);
			int b=Integer.parseInt(st[1]);
			if(a==0&&b==0)break;
			for(int i=1;i<=a;i++){int m=0;
			
				if(i%2==1){System.out.print("#");m++;}
				for(int l=1;l<=b-m;l++){
					if(l%2==1)System.out.print(".");
					else System.out.print("#");					
				}
			 System.out.println();
			}System.out.println();
		}
		

	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		for(;;){
			String s=br.readLine();
		    String[] st=s.split(" ");
			int a=Integer.parseInt(st[0]);
			int b=Integer.parseInt(st[1]);
			if(a==0&&b==0)break;
			for(int i=1;i<=a;i++){int m=0;
			
				if(i%2==1){System.out.print("#");m++;}
				for(int l=1;l<=b-m;l++){
					if(l%2==1)System.out.print(".");
					else System.out.print("#");					
				}
			 System.out.println();
			}System.out.println();
		}
		

	}
}