import java.util.Scanner;

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

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