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