import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    while(true){
      int a = scanner.nextInt();
      int b = scanner.nextInt();
      if(a == 0 && b == 0){
        break;
      }
      for(int j = 0; j < a; j++){
        if (j != 0) System.out.print("\n");
        for(int k = 0; k < b; k++){
        if((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)){
          System.out.print("#");
        }
        else{
          System.out.print(".");
        }
        }
      }
      System.out.println("\n");
    }
  }

} import java.util.*; util.* java public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    while(true){
      int a = scanner.nextInt();
      int b = scanner.nextInt();
      if(a == 0 && b == 0){
        break;
      }
      for(int j = 0; j < a; j++){
        if (j != 0) System.out.print("\n");
        for(int k = 0; k < b; k++){
        if((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)){
          System.out.print("#");
        }
        else{
          System.out.print(".");
        }
        }
      }
      System.out.println("\n");
    }
  }

} Main public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    while(true){
      int a = scanner.nextInt();
      int b = scanner.nextInt();
      if(a == 0 && b == 0){
        break;
      }
      for(int j = 0; j < a; j++){
        if (j != 0) System.out.print("\n");
        for(int k = 0; k < b; k++){
        if((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)){
          System.out.print("#");
        }
        else{
          System.out.print(".");
        }
        }
      }
      System.out.println("\n");
    }
  } main {
    Scanner scanner = new Scanner(System.in);
    while(true){
      int a = scanner.nextInt();
      int b = scanner.nextInt();
      if(a == 0 && b == 0){
        break;
      }
      for(int j = 0; j < a; j++){
        if (j != 0) System.out.print("\n");
        for(int k = 0; k < b; k++){
        if((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)){
          System.out.print("#");
        }
        else{
          System.out.print(".");
        }
        }
      }
      System.out.println("\n");
    }
  } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) while(true){
      int a = scanner.nextInt();
      int b = scanner.nextInt();
      if(a == 0 && b == 0){
        break;
      }
      for(int j = 0; j < a; j++){
        if (j != 0) System.out.print("\n");
        for(int k = 0; k < b; k++){
        if((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)){
          System.out.print("#");
        }
        else{
          System.out.print(".");
        }
        }
      }
      System.out.println("\n");
    } true {
      int a = scanner.nextInt();
      int b = scanner.nextInt();
      if(a == 0 && b == 0){
        break;
      }
      for(int j = 0; j < a; j++){
        if (j != 0) System.out.print("\n");
        for(int k = 0; k < b; k++){
        if((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)){
          System.out.print("#");
        }
        else{
          System.out.print(".");
        }
        }
      }
      System.out.println("\n");
    } int a = scanner.nextInt(); a scanner.nextInt() scanner.nextInt scanner int b = scanner.nextInt(); b scanner.nextInt() scanner.nextInt scanner if(a == 0 && b == 0){
        break;
      } a == 0 && b == 0 a == 0 a 0 b == 0 b 0 {
        break;
      } break; for(int j = 0; j < a; j++){
        if (j != 0) System.out.print("\n");
        for(int k = 0; k < b; k++){
        if((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)){
          System.out.print("#");
        }
        else{
          System.out.print(".");
        }
        }
      } int j = 0; int j = 0; j 0 j < a j a j++ j++ j {
        if (j != 0) System.out.print("\n");
        for(int k = 0; k < b; k++){
        if((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)){
          System.out.print("#");
        }
        else{
          System.out.print(".");
        }
        }
      } {
        if (j != 0) System.out.print("\n");
        for(int k = 0; k < b; k++){
        if((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)){
          System.out.print("#");
        }
        else{
          System.out.print(".");
        }
        }
      } if (j != 0) System.out.print("\n"); j != 0 j 0 System.out.print("\n") System.out.print System.out System System.out "\n" for(int k = 0; k < b; k++){
        if((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)){
          System.out.print("#");
        }
        else{
          System.out.print(".");
        }
        } int k = 0; int k = 0; k 0 k < b k b k++ k++ k {
        if((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)){
          System.out.print("#");
        }
        else{
          System.out.print(".");
        }
        } {
        if((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)){
          System.out.print("#");
        }
        else{
          System.out.print(".");
        }
        } if((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)){
          System.out.print("#");
        }
        else{
          System.out.print(".");
        } (j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1) (j % 2 == 0 && k % 2 == 0) j % 2 == 0 j % 2 j 2 0 k % 2 == 0 k % 2 k 2 0 (j % 2 == 1 && k % 2 == 1) j % 2 == 1 j % 2 j 2 1 k % 2 == 1 k % 2 k 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.println("\n") System.out.println System.out System System.out "\n" String[] args args public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    while(true){
      int a = scanner.nextInt();
      int b = scanner.nextInt();
      if(a == 0 && b == 0){
        break;
      }
      for(int j = 0; j < a; j++){
        if (j != 0) System.out.print("\n");
        for(int k = 0; k < b; k++){
        if((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)){
          System.out.print("#");
        }
        else{
          System.out.print(".");
        }
        }
      }
      System.out.println("\n");
    }
  }

} public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    while(true){
      int a = scanner.nextInt();
      int b = scanner.nextInt();
      if(a == 0 && b == 0){
        break;
      }
      for(int j = 0; j < a; j++){
        if (j != 0) System.out.print("\n");
        for(int k = 0; k < b; k++){
        if((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)){
          System.out.print("#");
        }
        else{
          System.out.print(".");
        }
        }
      }
      System.out.println("\n");
    }
  }

} Main
import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    while(true){
      int a = scanner.nextInt();
      int b = scanner.nextInt();
      if(a == 0 && b == 0){
        break;
      }
      for(int j = 0; j < a; j++){
        if (j != 0) System.out.print("\n");
        for(int k = 0; k < b; k++){
        if((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)){
          System.out.print("#");
        }
        else{
          System.out.print(".");
        }
        }
      }
      System.out.println("\n");
    }
  }

}