// ITP1_5-C Print a Chessboard
import java.util.Scanner;

class Main {
   public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      while (true) {
         int H = Integer.parseInt(sc.next());
         int W = Integer.parseInt(sc.next());
         if (H > 300 || W > 300) break;
         if (H == 0 && W == 0)   break;
         for (int i = 1; i <= H; i++) {
            for (int j = 1; j <= W; j++) {
               if ((i + j) % 2 == 0) {
                  System.out.print("#");
               } else if ((i + j) % 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 sc = new Scanner(System.in);
      while (true) {
         int H = Integer.parseInt(sc.next());
         int W = Integer.parseInt(sc.next());
         if (H > 300 || W > 300) break;
         if (H == 0 && W == 0)   break;
         for (int i = 1; i <= H; i++) {
            for (int j = 1; j <= W; j++) {
               if ((i + j) % 2 == 0) {
                  System.out.print("#");
               } else if ((i + j) % 2 == 1) {
                  System.out.print(".");
               }
            }
            System.out.println();
         }
         System.out.println();
      }
   }
} Main public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      while (true) {
         int H = Integer.parseInt(sc.next());
         int W = Integer.parseInt(sc.next());
         if (H > 300 || W > 300) break;
         if (H == 0 && W == 0)   break;
         for (int i = 1; i <= H; i++) {
            for (int j = 1; j <= W; j++) {
               if ((i + j) % 2 == 0) {
                  System.out.print("#");
               } else if ((i + j) % 2 == 1) {
                  System.out.print(".");
               }
            }
            System.out.println();
         }
         System.out.println();
      }
   } main {
      Scanner sc = new Scanner(System.in);
      while (true) {
         int H = Integer.parseInt(sc.next());
         int W = Integer.parseInt(sc.next());
         if (H > 300 || W > 300) break;
         if (H == 0 && W == 0)   break;
         for (int i = 1; i <= H; i++) {
            for (int j = 1; j <= W; j++) {
               if ((i + j) % 2 == 0) {
                  System.out.print("#");
               } else if ((i + j) % 2 == 1) {
                  System.out.print(".");
               }
            }
            System.out.println();
         }
         System.out.println();
      }
   } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while (true) {
         int H = Integer.parseInt(sc.next());
         int W = Integer.parseInt(sc.next());
         if (H > 300 || W > 300) break;
         if (H == 0 && W == 0)   break;
         for (int i = 1; i <= H; i++) {
            for (int j = 1; j <= W; j++) {
               if ((i + j) % 2 == 0) {
                  System.out.print("#");
               } else if ((i + j) % 2 == 1) {
                  System.out.print(".");
               }
            }
            System.out.println();
         }
         System.out.println();
      } true {
         int H = Integer.parseInt(sc.next());
         int W = Integer.parseInt(sc.next());
         if (H > 300 || W > 300) break;
         if (H == 0 && W == 0)   break;
         for (int i = 1; i <= H; i++) {
            for (int j = 1; j <= W; j++) {
               if ((i + j) % 2 == 0) {
                  System.out.print("#");
               } else if ((i + j) % 2 == 1) {
                  System.out.print(".");
               }
            }
            System.out.println();
         }
         System.out.println();
      } int H = Integer.parseInt(sc.next()); H Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int W = Integer.parseInt(sc.next()); W Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc if (H > 300 || W > 300) break; H > 300 || W > 300 H > 300 H 300 W > 300 W 300 break; if (H == 0 && W == 0)   break; H == 0 && W == 0 H == 0 H 0 W == 0 W 0 break; for (int i = 1; i <= H; i++) {
            for (int j = 1; j <= W; j++) {
               if ((i + j) % 2 == 0) {
                  System.out.print("#");
               } else if ((i + j) % 2 == 1) {
                  System.out.print(".");
               }
            }
            System.out.println();
         } int i = 1; int i = 1; i 1 i <= H i H i++ i++ i {
            for (int j = 1; j <= W; j++) {
               if ((i + j) % 2 == 0) {
                  System.out.print("#");
               } else if ((i + j) % 2 == 1) {
                  System.out.print(".");
               }
            }
            System.out.println();
         } {
            for (int j = 1; j <= W; j++) {
               if ((i + j) % 2 == 0) {
                  System.out.print("#");
               } else if ((i + j) % 2 == 1) {
                  System.out.print(".");
               }
            }
            System.out.println();
         } for (int j = 1; j <= W; j++) {
               if ((i + j) % 2 == 0) {
                  System.out.print("#");
               } else if ((i + j) % 2 == 1) {
                  System.out.print(".");
               }
            } int j = 1; int j = 1; j 1 j <= W j W j++ j++ j {
               if ((i + j) % 2 == 0) {
                  System.out.print("#");
               } else if ((i + j) % 2 == 1) {
                  System.out.print(".");
               }
            } {
               if ((i + j) % 2 == 0) {
                  System.out.print("#");
               } else if ((i + j) % 2 == 1) {
                  System.out.print(".");
               }
            } if ((i + j) % 2 == 0) {
                  System.out.print("#");
               } else if ((i + j) % 2 == 1) {
                  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 "#" if ((i + j) % 2 == 1) {
                  System.out.print(".");
               } (i + j) % 2 == 1 (i + j) % 2 (i + j) i j 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
// ITP1_5-C Print a Chessboard
import java.util.Scanner;

class Main {
   public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      while (true) {
         int H = Integer.parseInt(sc.next());
         int W = Integer.parseInt(sc.next());
         if (H > 300 || W > 300) break;
         if (H == 0 && W == 0)   break;
         for (int i = 1; i <= H; i++) {
            for (int j = 1; j <= W; j++) {
               if ((i + j) % 2 == 0) {
                  System.out.print("#");
               } else if ((i + j) % 2 == 1) {
                  System.out.print(".");
               }
            }
            System.out.println();
         }
         System.out.println();
      }
   }
}