import java.util.Scanner;

public class Main{ 
        public static void main(String[] args){
            int i=0,j,k,count=0;
            int a[];
            int b[];
            a = new int[100000];
            b = new int[100000];
                Scanner n = new Scanner(System.in);
                while(true){
                     a[i] = n.nextInt();
                     b[i] = n.nextInt();
                     if(a[i]==0 && b[i]==0){
                         break;
                     }
                     count++;
                     i++;
                }
                i=0;
                while(count>i){
                        for(k=0;k<a[i];k++){
                            if(k%2==0){
                            for(j=0;j<b[i];j++){
                                if(j%2==0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }else{
                            for(j=0;j<b[i];j++){
                                if(j%2!=0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }
                        }
                     i++;
                     System.out.printf("\n");
                }
        }
    } import java.util.Scanner; Scanner java.util public class Main{ 
        public static void main(String[] args){
            int i=0,j,k,count=0;
            int a[];
            int b[];
            a = new int[100000];
            b = new int[100000];
                Scanner n = new Scanner(System.in);
                while(true){
                     a[i] = n.nextInt();
                     b[i] = n.nextInt();
                     if(a[i]==0 && b[i]==0){
                         break;
                     }
                     count++;
                     i++;
                }
                i=0;
                while(count>i){
                        for(k=0;k<a[i];k++){
                            if(k%2==0){
                            for(j=0;j<b[i];j++){
                                if(j%2==0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }else{
                            for(j=0;j<b[i];j++){
                                if(j%2!=0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }
                        }
                     i++;
                     System.out.printf("\n");
                }
        }
    } Main public static void main(String[] args){
            int i=0,j,k,count=0;
            int a[];
            int b[];
            a = new int[100000];
            b = new int[100000];
                Scanner n = new Scanner(System.in);
                while(true){
                     a[i] = n.nextInt();
                     b[i] = n.nextInt();
                     if(a[i]==0 && b[i]==0){
                         break;
                     }
                     count++;
                     i++;
                }
                i=0;
                while(count>i){
                        for(k=0;k<a[i];k++){
                            if(k%2==0){
                            for(j=0;j<b[i];j++){
                                if(j%2==0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }else{
                            for(j=0;j<b[i];j++){
                                if(j%2!=0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }
                        }
                     i++;
                     System.out.printf("\n");
                }
        } main {
            int i=0,j,k,count=0;
            int a[];
            int b[];
            a = new int[100000];
            b = new int[100000];
                Scanner n = new Scanner(System.in);
                while(true){
                     a[i] = n.nextInt();
                     b[i] = n.nextInt();
                     if(a[i]==0 && b[i]==0){
                         break;
                     }
                     count++;
                     i++;
                }
                i=0;
                while(count>i){
                        for(k=0;k<a[i];k++){
                            if(k%2==0){
                            for(j=0;j<b[i];j++){
                                if(j%2==0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }else{
                            for(j=0;j<b[i];j++){
                                if(j%2!=0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }
                        }
                     i++;
                     System.out.printf("\n");
                }
        } int i=0 i 0 j j k k count=0; count 0 int a[]; a int b[]; b a = new int[100000] a new int[100000] 100000 b = new int[100000] b new int[100000] 100000 Scanner n = new Scanner(System.in); n new Scanner(System.in) while(true){
                     a[i] = n.nextInt();
                     b[i] = n.nextInt();
                     if(a[i]==0 && b[i]==0){
                         break;
                     }
                     count++;
                     i++;
                } true {
                     a[i] = n.nextInt();
                     b[i] = n.nextInt();
                     if(a[i]==0 && b[i]==0){
                         break;
                     }
                     count++;
                     i++;
                } a[i] = n.nextInt() a[i] a i n.nextInt() n.nextInt n b[i] = n.nextInt() b[i] b i n.nextInt() n.nextInt n if(a[i]==0 && b[i]==0){
                         break;
                     } a[i]==0 && b[i]==0 a[i]==0 a[i] a i 0 b[i]==0 b[i] b i 0 {
                         break;
                     } break; count++ count i++ i i=0 i 0 while(count>i){
                        for(k=0;k<a[i];k++){
                            if(k%2==0){
                            for(j=0;j<b[i];j++){
                                if(j%2==0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }else{
                            for(j=0;j<b[i];j++){
                                if(j%2!=0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }
                        }
                     i++;
                     System.out.printf("\n");
                } count>i count i {
                        for(k=0;k<a[i];k++){
                            if(k%2==0){
                            for(j=0;j<b[i];j++){
                                if(j%2==0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }else{
                            for(j=0;j<b[i];j++){
                                if(j%2!=0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }
                        }
                     i++;
                     System.out.printf("\n");
                } for(k=0;k<a[i];k++){
                            if(k%2==0){
                            for(j=0;j<b[i];j++){
                                if(j%2==0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }else{
                            for(j=0;j<b[i];j++){
                                if(j%2!=0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }
                        } k=0; k=0 k 0 k<a[i] k a[i] a i k++ k++ k {
                            if(k%2==0){
                            for(j=0;j<b[i];j++){
                                if(j%2==0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }else{
                            for(j=0;j<b[i];j++){
                                if(j%2!=0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }
                        } {
                            if(k%2==0){
                            for(j=0;j<b[i];j++){
                                if(j%2==0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }else{
                            for(j=0;j<b[i];j++){
                                if(j%2!=0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }
                        } if(k%2==0){
                            for(j=0;j<b[i];j++){
                                if(j%2==0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }else{
                            for(j=0;j<b[i];j++){
                                if(j%2!=0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        } k%2==0 k%2 k 2 0 {
                            for(j=0;j<b[i];j++){
                                if(j%2==0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        } for(j=0;j<b[i];j++){
                                if(j%2==0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            } j=0; j=0 j 0 j<b[i] j b[i] b i j++ j++ j {
                                if(j%2==0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            } {
                                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.printf("\n") System.out.printf System.out System System.out "\n" {
                            for(j=0;j<b[i];j++){
                                if(j%2!=0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        } for(j=0;j<b[i];j++){
                                if(j%2!=0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            } j=0; j=0 j 0 j<b[i] j b[i] b i j++ j++ j {
                                if(j%2!=0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            } {
                                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.printf("\n") System.out.printf System.out System System.out "\n" i++ i System.out.printf("\n") System.out.printf System.out System System.out "\n" String[] args args public class Main{ 
        public static void main(String[] args){
            int i=0,j,k,count=0;
            int a[];
            int b[];
            a = new int[100000];
            b = new int[100000];
                Scanner n = new Scanner(System.in);
                while(true){
                     a[i] = n.nextInt();
                     b[i] = n.nextInt();
                     if(a[i]==0 && b[i]==0){
                         break;
                     }
                     count++;
                     i++;
                }
                i=0;
                while(count>i){
                        for(k=0;k<a[i];k++){
                            if(k%2==0){
                            for(j=0;j<b[i];j++){
                                if(j%2==0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }else{
                            for(j=0;j<b[i];j++){
                                if(j%2!=0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }
                        }
                     i++;
                     System.out.printf("\n");
                }
        }
    } public class Main{ 
        public static void main(String[] args){
            int i=0,j,k,count=0;
            int a[];
            int b[];
            a = new int[100000];
            b = new int[100000];
                Scanner n = new Scanner(System.in);
                while(true){
                     a[i] = n.nextInt();
                     b[i] = n.nextInt();
                     if(a[i]==0 && b[i]==0){
                         break;
                     }
                     count++;
                     i++;
                }
                i=0;
                while(count>i){
                        for(k=0;k<a[i];k++){
                            if(k%2==0){
                            for(j=0;j<b[i];j++){
                                if(j%2==0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }else{
                            for(j=0;j<b[i];j++){
                                if(j%2!=0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }
                        }
                     i++;
                     System.out.printf("\n");
                }
        }
    } Main
import java.util.Scanner;

public class Main{ 
        public static void main(String[] args){
            int i=0,j,k,count=0;
            int a[];
            int b[];
            a = new int[100000];
            b = new int[100000];
                Scanner n = new Scanner(System.in);
                while(true){
                     a[i] = n.nextInt();
                     b[i] = n.nextInt();
                     if(a[i]==0 && b[i]==0){
                         break;
                     }
                     count++;
                     i++;
                }
                i=0;
                while(count>i){
                        for(k=0;k<a[i];k++){
                            if(k%2==0){
                            for(j=0;j<b[i];j++){
                                if(j%2==0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }else{
                            for(j=0;j<b[i];j++){
                                if(j%2!=0){
                                System.out.print("#");
                                }else{
                                    System.out.print(".");
                                }
                            }
                            System.out.printf("\n");
                        }
                        }
                     i++;
                     System.out.printf("\n");
                }
        }
    }
