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