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