import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int H =0;
    int W =0;
    while(true){
     H = sc.nextInt();
     W = sc.nextInt();

//  System.out.println("");
   if(H != 0 && W != 0){
    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.print("\n");
      }
      System.out.println("");
    }else{
      break;
    }
  }
}
//  sc.close();
  //System.exit(0);

  }
 import java.util.*; util.* java public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int H =0;
    int W =0;
    while(true){
     H = sc.nextInt();
     W = sc.nextInt();

//  System.out.println("");
   if(H != 0 && W != 0){
    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.print("\n");
      }
      System.out.println("");
    }else{
      break;
    }
  }
}
//  sc.close();
  //System.exit(0);

  } Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int H =0;
    int W =0;
    while(true){
     H = sc.nextInt();
     W = sc.nextInt();

//  System.out.println("");
   if(H != 0 && W != 0){
    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.print("\n");
      }
      System.out.println("");
    }else{
      break;
    }
  }
} main {
    Scanner sc = new Scanner(System.in);
    int H =0;
    int W =0;
    while(true){
     H = sc.nextInt();
     W = sc.nextInt();

//  System.out.println("");
   if(H != 0 && W != 0){
    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.print("\n");
      }
      System.out.println("");
    }else{
      break;
    }
  }
} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int H =0; H 0 int W =0; W 0 while(true){
     H = sc.nextInt();
     W = sc.nextInt();

//  System.out.println("");
   if(H != 0 && W != 0){
    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.print("\n");
      }
      System.out.println("");
    }else{
      break;
    }
  } true {
     H = sc.nextInt();
     W = sc.nextInt();

//  System.out.println("");
   if(H != 0 && W != 0){
    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.print("\n");
      }
      System.out.println("");
    }else{
      break;
    }
  } H = sc.nextInt() H sc.nextInt() sc.nextInt sc W = sc.nextInt() W sc.nextInt() sc.nextInt sc if(H != 0 && W != 0){
    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.print("\n");
      }
      System.out.println("");
    }else{
      break;
    } H != 0 && W != 0 H != 0 H 0 W != 0 W 0 {
    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.print("\n");
      }
      System.out.println("");
    } 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.print("\n");
      } 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.print("\n");
      } {
      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.print("\n");
      } 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 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 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 "" {
      break;
    } break; String[] args args public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int H =0;
    int W =0;
    while(true){
     H = sc.nextInt();
     W = sc.nextInt();

//  System.out.println("");
   if(H != 0 && W != 0){
    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.print("\n");
      }
      System.out.println("");
    }else{
      break;
    }
  }
}
//  sc.close();
  //System.exit(0);

  } public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int H =0;
    int W =0;
    while(true){
     H = sc.nextInt();
     W = sc.nextInt();

//  System.out.println("");
   if(H != 0 && W != 0){
    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.print("\n");
      }
      System.out.println("");
    }else{
      break;
    }
  }
}
//  sc.close();
  //System.exit(0);

  } Main
import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int H =0;
    int W =0;
    while(true){
     H = sc.nextInt();
     W = sc.nextInt();

//  System.out.println("");
   if(H != 0 && W != 0){
    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.print("\n");
      }
      System.out.println("");
    }else{
      break;
    }
  }
}
//  sc.close();
  //System.exit(0);

  }

