import java.util.Scanner;

public class Main
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        int i,k;

        while(true)
        {
            int H = sc.nextInt();
            int W = sc.nextInt();
    
            if(H==0 && W==0) break;

            for(i=0; i<H; i++)
            {
                for(k=0; k<W; k++)
                {
                    if(i%2 == 0)
                    {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    }                
                    else if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    }
                }
                System.out.print("\n");
            }

            System.out.printf("\n");
        }

        sc.close();
    }
} import java.util.Scanner; Scanner java.util public class Main
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        int i,k;

        while(true)
        {
            int H = sc.nextInt();
            int W = sc.nextInt();
    
            if(H==0 && W==0) break;

            for(i=0; i<H; i++)
            {
                for(k=0; k<W; k++)
                {
                    if(i%2 == 0)
                    {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    }                
                    else if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    }
                }
                System.out.print("\n");
            }

            System.out.printf("\n");
        }

        sc.close();
    }
} Main public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        int i,k;

        while(true)
        {
            int H = sc.nextInt();
            int W = sc.nextInt();
    
            if(H==0 && W==0) break;

            for(i=0; i<H; i++)
            {
                for(k=0; k<W; k++)
                {
                    if(i%2 == 0)
                    {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    }                
                    else if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    }
                }
                System.out.print("\n");
            }

            System.out.printf("\n");
        }

        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);
        int i,k;

        while(true)
        {
            int H = sc.nextInt();
            int W = sc.nextInt();
    
            if(H==0 && W==0) break;

            for(i=0; i<H; i++)
            {
                for(k=0; k<W; k++)
                {
                    if(i%2 == 0)
                    {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    }                
                    else if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    }
                }
                System.out.print("\n");
            }

            System.out.printf("\n");
        }

        sc.close();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int i i k; k while(true)
        {
            int H = sc.nextInt();
            int W = sc.nextInt();
    
            if(H==0 && W==0) break;

            for(i=0; i<H; i++)
            {
                for(k=0; k<W; k++)
                {
                    if(i%2 == 0)
                    {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    }                
                    else if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    }
                }
                System.out.print("\n");
            }

            System.out.printf("\n");
        } true {
            int H = sc.nextInt();
            int W = sc.nextInt();
    
            if(H==0 && W==0) break;

            for(i=0; i<H; i++)
            {
                for(k=0; k<W; k++)
                {
                    if(i%2 == 0)
                    {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    }                
                    else if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    }
                }
                System.out.print("\n");
            }

            System.out.printf("\n");
        } 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(i=0; i<H; i++)
            {
                for(k=0; k<W; k++)
                {
                    if(i%2 == 0)
                    {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    }                
                    else if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    }
                }
                System.out.print("\n");
            } i=0; i=0 i 0 i<H i H i++ i++ i {
                for(k=0; k<W; k++)
                {
                    if(i%2 == 0)
                    {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    }                
                    else if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    }
                }
                System.out.print("\n");
            } {
                for(k=0; k<W; k++)
                {
                    if(i%2 == 0)
                    {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    }                
                    else if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    }
                }
                System.out.print("\n");
            } for(k=0; k<W; k++)
                {
                    if(i%2 == 0)
                    {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    }                
                    else if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    }
                } k=0; k=0 k 0 k<W k W k++ k++ k {
                    if(i%2 == 0)
                    {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    }                
                    else if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    }
                } {
                    if(i%2 == 0)
                    {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    }                
                    else if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    }
                } if(i%2 == 0)
                    {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    }                
                    else if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    } i%2 == 0 i%2 i 2 0 {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    } if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf("."); k%2==0 k%2 k 2 0 System.out.printf("#") System.out.printf System.out System System.out "#" if(k%2==1) System.out.printf("."); k%2==1 k%2 k 2 1 System.out.printf(".") System.out.printf System.out System System.out "." if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    } i%2 == 1 i%2 i 2 1 {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    } if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#"); k%2==0 k%2 k 2 0 System.out.printf(".") System.out.printf System.out System System.out "." if(k%2==1) System.out.printf("#"); k%2==1 k%2 k 2 1 System.out.printf("#") System.out.printf System.out System System.out "#" System.out.print("\n") System.out.print System.out System System.out "\n" System.out.printf("\n") System.out.printf System.out System System.out "\n" sc.close() sc.close sc String[] args args public class Main
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        int i,k;

        while(true)
        {
            int H = sc.nextInt();
            int W = sc.nextInt();
    
            if(H==0 && W==0) break;

            for(i=0; i<H; i++)
            {
                for(k=0; k<W; k++)
                {
                    if(i%2 == 0)
                    {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    }                
                    else if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    }
                }
                System.out.print("\n");
            }

            System.out.printf("\n");
        }

        sc.close();
    }
} public class Main
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        int i,k;

        while(true)
        {
            int H = sc.nextInt();
            int W = sc.nextInt();
    
            if(H==0 && W==0) break;

            for(i=0; i<H; i++)
            {
                for(k=0; k<W; k++)
                {
                    if(i%2 == 0)
                    {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    }                
                    else if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    }
                }
                System.out.print("\n");
            }

            System.out.printf("\n");
        }

        sc.close();
    }
} Main
import java.util.Scanner;

public class Main
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        int i,k;

        while(true)
        {
            int H = sc.nextInt();
            int W = sc.nextInt();
    
            if(H==0 && W==0) break;

            for(i=0; i<H; i++)
            {
                for(k=0; k<W; k++)
                {
                    if(i%2 == 0)
                    {
                        if(k%2==0) System.out.printf("#");
                        else if(k%2==1) System.out.printf(".");
                    }                
                    else if(i%2 == 1)
                    {
                        if(k%2==0) System.out.printf(".");
                        else if(k%2==1) System.out.printf("#");
                    }
                }
                System.out.print("\n");
            }

            System.out.printf("\n");
        }

        sc.close();
    }
}
