import java.util.Scanner;

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

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