import java.util.Scanner;
public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    while (true) {
      int H = sc.nextInt();
      int W= sc.nextInt();

      if (H == 0 && W == 0) { break; }

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

      if (H == 0 && W == 0) { break; }

      for(int i=1; i <= H; i++){
        if(i % 2 == 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print(".");
              break;
            } else {
              System.out.print(".");
              j++;
              if(j == W){ break; }
              System.out.print("#");
              j++;
              if(j == W){ break; }
            }
          }
        }
        if(i % 2 != 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print("#");
              break;
            } else {
              System.out.print("#");
              j++;
              if(j == W){ break; }
              System.out.print(".");
              j++;
              if(j == W){ break; }
            }
          }
        }
        System.out.print("\n");
      }
      System.out.printf("\n");
    }
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    while (true) {
      int H = sc.nextInt();
      int W= sc.nextInt();

      if (H == 0 && W == 0) { break; }

      for(int i=1; i <= H; i++){
        if(i % 2 == 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print(".");
              break;
            } else {
              System.out.print(".");
              j++;
              if(j == W){ break; }
              System.out.print("#");
              j++;
              if(j == W){ break; }
            }
          }
        }
        if(i % 2 != 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print("#");
              break;
            } else {
              System.out.print("#");
              j++;
              if(j == W){ break; }
              System.out.print(".");
              j++;
              if(j == W){ break; }
            }
          }
        }
        System.out.print("\n");
      }
      System.out.printf("\n");
    }
  } main {
    Scanner sc = new Scanner(System.in);
    while (true) {
      int H = sc.nextInt();
      int W= sc.nextInt();

      if (H == 0 && W == 0) { break; }

      for(int i=1; i <= H; i++){
        if(i % 2 == 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print(".");
              break;
            } else {
              System.out.print(".");
              j++;
              if(j == W){ break; }
              System.out.print("#");
              j++;
              if(j == W){ break; }
            }
          }
        }
        if(i % 2 != 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print("#");
              break;
            } else {
              System.out.print("#");
              j++;
              if(j == W){ break; }
              System.out.print(".");
              j++;
              if(j == W){ break; }
            }
          }
        }
        System.out.print("\n");
      }
      System.out.printf("\n");
    }
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while (true) {
      int H = sc.nextInt();
      int W= sc.nextInt();

      if (H == 0 && W == 0) { break; }

      for(int i=1; i <= H; i++){
        if(i % 2 == 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print(".");
              break;
            } else {
              System.out.print(".");
              j++;
              if(j == W){ break; }
              System.out.print("#");
              j++;
              if(j == W){ break; }
            }
          }
        }
        if(i % 2 != 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print("#");
              break;
            } else {
              System.out.print("#");
              j++;
              if(j == W){ break; }
              System.out.print(".");
              j++;
              if(j == W){ break; }
            }
          }
        }
        System.out.print("\n");
      }
      System.out.printf("\n");
    } true {
      int H = sc.nextInt();
      int W= sc.nextInt();

      if (H == 0 && W == 0) { break; }

      for(int i=1; i <= H; i++){
        if(i % 2 == 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print(".");
              break;
            } else {
              System.out.print(".");
              j++;
              if(j == W){ break; }
              System.out.print("#");
              j++;
              if(j == W){ break; }
            }
          }
        }
        if(i % 2 != 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print("#");
              break;
            } else {
              System.out.print("#");
              j++;
              if(j == W){ break; }
              System.out.print(".");
              j++;
              if(j == W){ break; }
            }
          }
        }
        System.out.print("\n");
      }
      System.out.printf("\n");
    } int H = sc.nextInt(); H sc.nextInt() sc.nextInt sc int 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; } break; for(int i=1; i <= H; i++){
        if(i % 2 == 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print(".");
              break;
            } else {
              System.out.print(".");
              j++;
              if(j == W){ break; }
              System.out.print("#");
              j++;
              if(j == W){ break; }
            }
          }
        }
        if(i % 2 != 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print("#");
              break;
            } else {
              System.out.print("#");
              j++;
              if(j == W){ break; }
              System.out.print(".");
              j++;
              if(j == W){ break; }
            }
          }
        }
        System.out.print("\n");
      } int i=1; int i=1; i 1 i <= H i H i++ i++ i {
        if(i % 2 == 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print(".");
              break;
            } else {
              System.out.print(".");
              j++;
              if(j == W){ break; }
              System.out.print("#");
              j++;
              if(j == W){ break; }
            }
          }
        }
        if(i % 2 != 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print("#");
              break;
            } else {
              System.out.print("#");
              j++;
              if(j == W){ break; }
              System.out.print(".");
              j++;
              if(j == W){ break; }
            }
          }
        }
        System.out.print("\n");
      } {
        if(i % 2 == 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print(".");
              break;
            } else {
              System.out.print(".");
              j++;
              if(j == W){ break; }
              System.out.print("#");
              j++;
              if(j == W){ break; }
            }
          }
        }
        if(i % 2 != 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print("#");
              break;
            } else {
              System.out.print("#");
              j++;
              if(j == W){ break; }
              System.out.print(".");
              j++;
              if(j == W){ break; }
            }
          }
        }
        System.out.print("\n");
      } if(i % 2 == 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print(".");
              break;
            } else {
              System.out.print(".");
              j++;
              if(j == W){ break; }
              System.out.print("#");
              j++;
              if(j == W){ break; }
            }
          }
        } i % 2 == 0 i % 2 i 2 0 {
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print(".");
              break;
            } else {
              System.out.print(".");
              j++;
              if(j == W){ break; }
              System.out.print("#");
              j++;
              if(j == W){ break; }
            }
          }
        } int j = 0; j 0 while(j <= W){
            if(W == 1){
              System.out.print(".");
              break;
            } else {
              System.out.print(".");
              j++;
              if(j == W){ break; }
              System.out.print("#");
              j++;
              if(j == W){ break; }
            }
          } j <= W j W {
            if(W == 1){
              System.out.print(".");
              break;
            } else {
              System.out.print(".");
              j++;
              if(j == W){ break; }
              System.out.print("#");
              j++;
              if(j == W){ break; }
            }
          } if(W == 1){
              System.out.print(".");
              break;
            } else {
              System.out.print(".");
              j++;
              if(j == W){ break; }
              System.out.print("#");
              j++;
              if(j == W){ break; }
            } W == 1 W 1 {
              System.out.print(".");
              break;
            } System.out.print(".") System.out.print System.out System System.out "." break; {
              System.out.print(".");
              j++;
              if(j == W){ break; }
              System.out.print("#");
              j++;
              if(j == W){ break; }
            } System.out.print(".") System.out.print System.out System System.out "." j++ j if(j == W){ break; } j == W j W { break; } break; System.out.print("#") System.out.print System.out System System.out "#" j++ j if(j == W){ break; } j == W j W { break; } break; if(i % 2 != 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print("#");
              break;
            } else {
              System.out.print("#");
              j++;
              if(j == W){ break; }
              System.out.print(".");
              j++;
              if(j == W){ break; }
            }
          }
        } i % 2 != 0 i % 2 i 2 0 {
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print("#");
              break;
            } else {
              System.out.print("#");
              j++;
              if(j == W){ break; }
              System.out.print(".");
              j++;
              if(j == W){ break; }
            }
          }
        } int j = 0; j 0 while(j <= W){
            if(W == 1){
              System.out.print("#");
              break;
            } else {
              System.out.print("#");
              j++;
              if(j == W){ break; }
              System.out.print(".");
              j++;
              if(j == W){ break; }
            }
          } j <= W j W {
            if(W == 1){
              System.out.print("#");
              break;
            } else {
              System.out.print("#");
              j++;
              if(j == W){ break; }
              System.out.print(".");
              j++;
              if(j == W){ break; }
            }
          } if(W == 1){
              System.out.print("#");
              break;
            } else {
              System.out.print("#");
              j++;
              if(j == W){ break; }
              System.out.print(".");
              j++;
              if(j == W){ break; }
            } W == 1 W 1 {
              System.out.print("#");
              break;
            } System.out.print("#") System.out.print System.out System System.out "#" break; {
              System.out.print("#");
              j++;
              if(j == W){ break; }
              System.out.print(".");
              j++;
              if(j == W){ break; }
            } System.out.print("#") System.out.print System.out System System.out "#" j++ j if(j == W){ break; } j == W j W { break; } break; System.out.print(".") System.out.print System.out System System.out "." j++ j if(j == W){ break; } j == W j W { break; } break; System.out.print("\n") System.out.print System.out System System.out "\n" System.out.printf("\n") System.out.printf System.out System System.out "\n" String[] args args public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    while (true) {
      int H = sc.nextInt();
      int W= sc.nextInt();

      if (H == 0 && W == 0) { break; }

      for(int i=1; i <= H; i++){
        if(i % 2 == 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print(".");
              break;
            } else {
              System.out.print(".");
              j++;
              if(j == W){ break; }
              System.out.print("#");
              j++;
              if(j == W){ break; }
            }
          }
        }
        if(i % 2 != 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print("#");
              break;
            } else {
              System.out.print("#");
              j++;
              if(j == W){ break; }
              System.out.print(".");
              j++;
              if(j == W){ break; }
            }
          }
        }
        System.out.print("\n");
      }
      System.out.printf("\n");
    }
  }
} public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    while (true) {
      int H = sc.nextInt();
      int W= sc.nextInt();

      if (H == 0 && W == 0) { break; }

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

      if (H == 0 && W == 0) { break; }

      for(int i=1; i <= H; i++){
        if(i % 2 == 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print(".");
              break;
            } else {
              System.out.print(".");
              j++;
              if(j == W){ break; }
              System.out.print("#");
              j++;
              if(j == W){ break; }
            }
          }
        }
        if(i % 2 != 0){
          int j = 0;
          while(j <= W){
            if(W == 1){
              System.out.print("#");
              break;
            } else {
              System.out.print("#");
              j++;
              if(j == W){ break; }
              System.out.print(".");
              j++;
              if(j == W){ break; }
            }
          }
        }
        System.out.print("\n");
      }
      System.out.printf("\n");
    }
  }
}

