public class Main{
  public void run(java.io.InputStream in, java.io.PrintStream out){
    java.util.Scanner sc = new java.util.Scanner(in);
/*answer*/
    int h, w;
    int i, j;

    for(;;){
      h = sc.nextInt();
      w = sc.nextInt();
      if(h == 0 && w == 0)break;

      for(i = 0;i < h;i++){
        for(j = 0;j < w;j++){
          if((i + j) % 2 == 0){
            System.out.print("#");
          }else{
            System.out.print(".");
          }
        }
        System.out.println();
      }
      System.out.println();
    }

    sc.close();
  }
  public static void main(String[] args){
    (new Main()).run(System.in, System.out);
  }
} public class Main{
  public void run(java.io.InputStream in, java.io.PrintStream out){
    java.util.Scanner sc = new java.util.Scanner(in);
/*answer*/
    int h, w;
    int i, j;

    for(;;){
      h = sc.nextInt();
      w = sc.nextInt();
      if(h == 0 && w == 0)break;

      for(i = 0;i < h;i++){
        for(j = 0;j < w;j++){
          if((i + j) % 2 == 0){
            System.out.print("#");
          }else{
            System.out.print(".");
          }
        }
        System.out.println();
      }
      System.out.println();
    }

    sc.close();
  }
  public static void main(String[] args){
    (new Main()).run(System.in, System.out);
  }
} Main public void run(java.io.InputStream in, java.io.PrintStream out){
    java.util.Scanner sc = new java.util.Scanner(in);
/*answer*/
    int h, w;
    int i, j;

    for(;;){
      h = sc.nextInt();
      w = sc.nextInt();
      if(h == 0 && w == 0)break;

      for(i = 0;i < h;i++){
        for(j = 0;j < w;j++){
          if((i + j) % 2 == 0){
            System.out.print("#");
          }else{
            System.out.print(".");
          }
        }
        System.out.println();
      }
      System.out.println();
    }

    sc.close();
  } run {
    java.util.Scanner sc = new java.util.Scanner(in);
/*answer*/
    int h, w;
    int i, j;

    for(;;){
      h = sc.nextInt();
      w = sc.nextInt();
      if(h == 0 && w == 0)break;

      for(i = 0;i < h;i++){
        for(j = 0;j < w;j++){
          if((i + j) % 2 == 0){
            System.out.print("#");
          }else{
            System.out.print(".");
          }
        }
        System.out.println();
      }
      System.out.println();
    }

    sc.close();
  } java.util.Scanner sc = new java.util.Scanner(in); sc new java.util.Scanner(in) int h h w; w int i i j; j for(;;){
      h = sc.nextInt();
      w = sc.nextInt();
      if(h == 0 && w == 0)break;

      for(i = 0;i < h;i++){
        for(j = 0;j < w;j++){
          if((i + j) % 2 == 0){
            System.out.print("#");
          }else{
            System.out.print(".");
          }
        }
        System.out.println();
      }
      System.out.println();
    } ; {
      h = sc.nextInt();
      w = sc.nextInt();
      if(h == 0 && w == 0)break;

      for(i = 0;i < h;i++){
        for(j = 0;j < w;j++){
          if((i + j) % 2 == 0){
            System.out.print("#");
          }else{
            System.out.print(".");
          }
        }
        System.out.println();
      }
      System.out.println();
    } {
      h = sc.nextInt();
      w = sc.nextInt();
      if(h == 0 && w == 0)break;

      for(i = 0;i < h;i++){
        for(j = 0;j < w;j++){
          if((i + j) % 2 == 0){
            System.out.print("#");
          }else{
            System.out.print(".");
          }
        }
        System.out.println();
      }
      System.out.println();
    } h = sc.nextInt() h sc.nextInt() sc.nextInt sc w = sc.nextInt() w sc.nextInt() sc.nextInt sc if(h == 0 && w == 0)break; 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 + j) % 2 == 0){
            System.out.print("#");
          }else{
            System.out.print(".");
          }
        }
        System.out.println();
      } i = 0; i = 0 i 0 i < h i h i++ i++ i {
        for(j = 0;j < w;j++){
          if((i + j) % 2 == 0){
            System.out.print("#");
          }else{
            System.out.print(".");
          }
        }
        System.out.println();
      } {
        for(j = 0;j < w;j++){
          if((i + j) % 2 == 0){
            System.out.print("#");
          }else{
            System.out.print(".");
          }
        }
        System.out.println();
      } for(j = 0;j < w;j++){
          if((i + j) % 2 == 0){
            System.out.print("#");
          }else{
            System.out.print(".");
          }
        } j = 0; j = 0 j 0 j < w j w 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 sc.close() sc.close sc java.io.InputStream in in java.io.PrintStream out out public static void main(String[] args){
    (new Main()).run(System.in, System.out);
  } main {
    (new Main()).run(System.in, System.out);
  } (new Main()).run(System.in, System.out) (new Main()).run (new Main()) System.in System System.in System.out System System.out String[] args args public class Main{
  public void run(java.io.InputStream in, java.io.PrintStream out){
    java.util.Scanner sc = new java.util.Scanner(in);
/*answer*/
    int h, w;
    int i, j;

    for(;;){
      h = sc.nextInt();
      w = sc.nextInt();
      if(h == 0 && w == 0)break;

      for(i = 0;i < h;i++){
        for(j = 0;j < w;j++){
          if((i + j) % 2 == 0){
            System.out.print("#");
          }else{
            System.out.print(".");
          }
        }
        System.out.println();
      }
      System.out.println();
    }

    sc.close();
  }
  public static void main(String[] args){
    (new Main()).run(System.in, System.out);
  }
} public class Main{
  public void run(java.io.InputStream in, java.io.PrintStream out){
    java.util.Scanner sc = new java.util.Scanner(in);
/*answer*/
    int h, w;
    int i, j;

    for(;;){
      h = sc.nextInt();
      w = sc.nextInt();
      if(h == 0 && w == 0)break;

      for(i = 0;i < h;i++){
        for(j = 0;j < w;j++){
          if((i + j) % 2 == 0){
            System.out.print("#");
          }else{
            System.out.print(".");
          }
        }
        System.out.println();
      }
      System.out.println();
    }

    sc.close();
  }
  public static void main(String[] args){
    (new Main()).run(System.in, System.out);
  }
} Main
public class Main{
  public void run(java.io.InputStream in, java.io.PrintStream out){
    java.util.Scanner sc = new java.util.Scanner(in);
/*answer*/
    int h, w;
    int i, j;

    for(;;){
      h = sc.nextInt();
      w = sc.nextInt();
      if(h == 0 && w == 0)break;

      for(i = 0;i < h;i++){
        for(j = 0;j < w;j++){
          if((i + j) % 2 == 0){
            System.out.print("#");
          }else{
            System.out.print(".");
          }
        }
        System.out.println();
      }
      System.out.println();
    }

    sc.close();
  }
  public static void main(String[] args){
    (new Main()).run(System.in, System.out);
  }
}