import java.util.Scanner;

     class Main{
        public static void main(String args[]){
           Scanner scan = new Scanner(System.in);

              while(true){

                 int h =scan.nextInt();
                 int w =scan.nextInt();


                 if(h==0&&w==0){
                 break;
                 } else {

                   for(int h1 =0;h1<h;h1++){

                    for(int w1 =0;w1<w;w1++){

                       int i =h1+w1;

                       if(i%2==0){
                       System.out.print("#");
                       }

                       if(i%2==1){
                       System.out.print(".");
                       }
                    }
                     System.out.println();
                   }
                      System.out.println();
                   }
              }
        }
     }
 import java.util.Scanner; Scanner java.util class Main{
        public static void main(String args[]){
           Scanner scan = new Scanner(System.in);

              while(true){

                 int h =scan.nextInt();
                 int w =scan.nextInt();


                 if(h==0&&w==0){
                 break;
                 } else {

                   for(int h1 =0;h1<h;h1++){

                    for(int w1 =0;w1<w;w1++){

                       int i =h1+w1;

                       if(i%2==0){
                       System.out.print("#");
                       }

                       if(i%2==1){
                       System.out.print(".");
                       }
                    }
                     System.out.println();
                   }
                      System.out.println();
                   }
              }
        }
     } Main public static void main(String args[]){
           Scanner scan = new Scanner(System.in);

              while(true){

                 int h =scan.nextInt();
                 int w =scan.nextInt();


                 if(h==0&&w==0){
                 break;
                 } else {

                   for(int h1 =0;h1<h;h1++){

                    for(int w1 =0;w1<w;w1++){

                       int i =h1+w1;

                       if(i%2==0){
                       System.out.print("#");
                       }

                       if(i%2==1){
                       System.out.print(".");
                       }
                    }
                     System.out.println();
                   }
                      System.out.println();
                   }
              }
        } main {
           Scanner scan = new Scanner(System.in);

              while(true){

                 int h =scan.nextInt();
                 int w =scan.nextInt();


                 if(h==0&&w==0){
                 break;
                 } else {

                   for(int h1 =0;h1<h;h1++){

                    for(int w1 =0;w1<w;w1++){

                       int i =h1+w1;

                       if(i%2==0){
                       System.out.print("#");
                       }

                       if(i%2==1){
                       System.out.print(".");
                       }
                    }
                     System.out.println();
                   }
                      System.out.println();
                   }
              }
        } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) while(true){

                 int h =scan.nextInt();
                 int w =scan.nextInt();


                 if(h==0&&w==0){
                 break;
                 } else {

                   for(int h1 =0;h1<h;h1++){

                    for(int w1 =0;w1<w;w1++){

                       int i =h1+w1;

                       if(i%2==0){
                       System.out.print("#");
                       }

                       if(i%2==1){
                       System.out.print(".");
                       }
                    }
                     System.out.println();
                   }
                      System.out.println();
                   }
              } true {

                 int h =scan.nextInt();
                 int w =scan.nextInt();


                 if(h==0&&w==0){
                 break;
                 } else {

                   for(int h1 =0;h1<h;h1++){

                    for(int w1 =0;w1<w;w1++){

                       int i =h1+w1;

                       if(i%2==0){
                       System.out.print("#");
                       }

                       if(i%2==1){
                       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;
                 } else {

                   for(int h1 =0;h1<h;h1++){

                    for(int w1 =0;w1<w;w1++){

                       int i =h1+w1;

                       if(i%2==0){
                       System.out.print("#");
                       }

                       if(i%2==1){
                       System.out.print(".");
                       }
                    }
                     System.out.println();
                   }
                      System.out.println();
                   } h==0&&w==0 h==0 h 0 w==0 w 0 {
                 break;
                 } break; {

                   for(int h1 =0;h1<h;h1++){

                    for(int w1 =0;w1<w;w1++){

                       int i =h1+w1;

                       if(i%2==0){
                       System.out.print("#");
                       }

                       if(i%2==1){
                       System.out.print(".");
                       }
                    }
                     System.out.println();
                   }
                      System.out.println();
                   } for(int h1 =0;h1<h;h1++){

                    for(int w1 =0;w1<w;w1++){

                       int i =h1+w1;

                       if(i%2==0){
                       System.out.print("#");
                       }

                       if(i%2==1){
                       System.out.print(".");
                       }
                    }
                     System.out.println();
                   } int h1 =0; int h1 =0; h1 0 h1<h h1 h h1++ h1++ h1 {

                    for(int w1 =0;w1<w;w1++){

                       int i =h1+w1;

                       if(i%2==0){
                       System.out.print("#");
                       }

                       if(i%2==1){
                       System.out.print(".");
                       }
                    }
                     System.out.println();
                   } {

                    for(int w1 =0;w1<w;w1++){

                       int i =h1+w1;

                       if(i%2==0){
                       System.out.print("#");
                       }

                       if(i%2==1){
                       System.out.print(".");
                       }
                    }
                     System.out.println();
                   } for(int w1 =0;w1<w;w1++){

                       int i =h1+w1;

                       if(i%2==0){
                       System.out.print("#");
                       }

                       if(i%2==1){
                       System.out.print(".");
                       }
                    } int w1 =0; int w1 =0; w1 0 w1<w w1 w w1++ w1++ w1 {

                       int i =h1+w1;

                       if(i%2==0){
                       System.out.print("#");
                       }

                       if(i%2==1){
                       System.out.print(".");
                       }
                    } {

                       int i =h1+w1;

                       if(i%2==0){
                       System.out.print("#");
                       }

                       if(i%2==1){
                       System.out.print(".");
                       }
                    } int i =h1+w1; i h1+w1 h1 w1 if(i%2==0){
                       System.out.print("#");
                       } i%2==0 i%2 i 2 0 {
                       System.out.print("#");
                       } System.out.print("#") System.out.print System.out System System.out "#" if(i%2==1){
                       System.out.print(".");
                       } i%2==1 i%2 i 2 1 {
                       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
import java.util.Scanner;

     class Main{
        public static void main(String args[]){
           Scanner scan = new Scanner(System.in);

              while(true){

                 int h =scan.nextInt();
                 int w =scan.nextInt();


                 if(h==0&&w==0){
                 break;
                 } else {

                   for(int h1 =0;h1<h;h1++){

                    for(int w1 =0;w1<w;w1++){

                       int i =h1+w1;

                       if(i%2==0){
                       System.out.print("#");
                       }

                       if(i%2==1){
                       System.out.print(".");
                       }
                    }
                     System.out.println();
                   }
                      System.out.println();
                   }
              }
        }
     }

