import 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++) {
               int cnt = i%2;
              for (int j = 0; j < W; j++) {
                if(cnt %2 ==0)
                {
                    System.out.print("#");
                }
                else{
                    System.out.print(".");
                }
                cnt ++;
              } 
              System.out.println();

           }
           System.out.println();
        }
        sc.close();
    }
} import java.util.*; util.* java 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++) {
               int cnt = i%2;
              for (int j = 0; j < W; j++) {
                if(cnt %2 ==0)
                {
                    System.out.print("#");
                }
                else{
                    System.out.print(".");
                }
                cnt ++;
              } 
              System.out.println();

           }
           System.out.println();
        }
        sc.close();
    }
} 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++) {
               int cnt = i%2;
              for (int j = 0; j < W; j++) {
                if(cnt %2 ==0)
                {
                    System.out.print("#");
                }
                else{
                    System.out.print(".");
                }
                cnt ++;
              } 
              System.out.println();

           }
           System.out.println();
        }
        sc.close();
    } 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++) {
               int cnt = i%2;
              for (int j = 0; j < W; j++) {
                if(cnt %2 ==0)
                {
                    System.out.print("#");
                }
                else{
                    System.out.print(".");
                }
                cnt ++;
              } 
              System.out.println();

           }
           System.out.println();
        }
        sc.close();
    } 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++) {
               int cnt = i%2;
              for (int j = 0; j < W; j++) {
                if(cnt %2 ==0)
                {
                    System.out.print("#");
                }
                else{
                    System.out.print(".");
                }
                cnt ++;
              } 
              System.out.println();

           }
           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++) {
               int cnt = i%2;
              for (int j = 0; j < W; j++) {
                if(cnt %2 ==0)
                {
                    System.out.print("#");
                }
                else{
                    System.out.print(".");
                }
                cnt ++;
              } 
              System.out.println();

           }
           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;
           } break; for (int i = 0; i < H; i++) {
               int cnt = i%2;
              for (int j = 0; j < W; j++) {
                if(cnt %2 ==0)
                {
                    System.out.print("#");
                }
                else{
                    System.out.print(".");
                }
                cnt ++;
              } 
              System.out.println();

           } int i = 0; int i = 0; i 0 i < H i H i++ i++ i {
               int cnt = i%2;
              for (int j = 0; j < W; j++) {
                if(cnt %2 ==0)
                {
                    System.out.print("#");
                }
                else{
                    System.out.print(".");
                }
                cnt ++;
              } 
              System.out.println();

           } {
               int cnt = i%2;
              for (int j = 0; j < W; j++) {
                if(cnt %2 ==0)
                {
                    System.out.print("#");
                }
                else{
                    System.out.print(".");
                }
                cnt ++;
              } 
              System.out.println();

           } int cnt = i%2; cnt i%2 i 2 for (int j = 0; j < W; j++) {
                if(cnt %2 ==0)
                {
                    System.out.print("#");
                }
                else{
                    System.out.print(".");
                }
                cnt ++;
              } int j = 0; int j = 0; j 0 j < W j W j++ j++ j {
                if(cnt %2 ==0)
                {
                    System.out.print("#");
                }
                else{
                    System.out.print(".");
                }
                cnt ++;
              } {
                if(cnt %2 ==0)
                {
                    System.out.print("#");
                }
                else{
                    System.out.print(".");
                }
                cnt ++;
              } if(cnt %2 ==0)
                {
                    System.out.print("#");
                }
                else{
                    System.out.print(".");
                } cnt %2 ==0 cnt %2 cnt 2 0 {
                    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 "." cnt ++ cnt System.out.println() System.out.println System.out System System.out System.out.println() System.out.println System.out System System.out sc.close() sc.close sc 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++) {
               int cnt = i%2;
              for (int j = 0; j < W; j++) {
                if(cnt %2 ==0)
                {
                    System.out.print("#");
                }
                else{
                    System.out.print(".");
                }
                cnt ++;
              } 
              System.out.println();

           }
           System.out.println();
        }
        sc.close();
    }
} 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++) {
               int cnt = i%2;
              for (int j = 0; j < W; j++) {
                if(cnt %2 ==0)
                {
                    System.out.print("#");
                }
                else{
                    System.out.print(".");
                }
                cnt ++;
              } 
              System.out.println();

           }
           System.out.println();
        }
        sc.close();
    }
} Main
import 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++) {
               int cnt = i%2;
              for (int j = 0; j < W; j++) {
                if(cnt %2 ==0)
                {
                    System.out.print("#");
                }
                else{
                    System.out.print(".");
                }
                cnt ++;
              } 
              System.out.println();

           }
           System.out.println();
        }
        sc.close();
    }
}
