import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        int h=sc.nextInt();
        int w=sc.nextInt();
        while(h!=0 || w!=0){
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    if(i%2==0){
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }else{
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }
                }
                System.out.printf("\n");
            }
            h=sc.nextInt();
            w=sc.nextInt();
            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 h=sc.nextInt();
        int w=sc.nextInt();
        while(h!=0 || w!=0){
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    if(i%2==0){
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }else{
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }
                }
                System.out.printf("\n");
            }
            h=sc.nextInt();
            w=sc.nextInt();
            System.out.printf("\n");
        }
        sc.close();

    }
} Main public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        int h=sc.nextInt();
        int w=sc.nextInt();
        while(h!=0 || w!=0){
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    if(i%2==0){
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }else{
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }
                }
                System.out.printf("\n");
            }
            h=sc.nextInt();
            w=sc.nextInt();
            System.out.printf("\n");
        }
        sc.close();

    } main {
        Scanner sc=new Scanner(System.in);
        int h=sc.nextInt();
        int w=sc.nextInt();
        while(h!=0 || w!=0){
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    if(i%2==0){
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }else{
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }
                }
                System.out.printf("\n");
            }
            h=sc.nextInt();
            w=sc.nextInt();
            System.out.printf("\n");
        }
        sc.close();

    } Scanner sc=new Scanner(System.in); sc new Scanner(System.in) int h=sc.nextInt(); h sc.nextInt() sc.nextInt sc int w=sc.nextInt(); w sc.nextInt() sc.nextInt sc while(h!=0 || w!=0){
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    if(i%2==0){
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }else{
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }
                }
                System.out.printf("\n");
            }
            h=sc.nextInt();
            w=sc.nextInt();
            System.out.printf("\n");
        } h!=0 || w!=0 h!=0 h 0 w!=0 w 0 {
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    if(i%2==0){
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }else{
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }
                }
                System.out.printf("\n");
            }
            h=sc.nextInt();
            w=sc.nextInt();
            System.out.printf("\n");
        } for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    if(i%2==0){
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }else{
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }
                }
                System.out.printf("\n");
            } int i=0; int i=0; i 0 i<h i h i++ i++ i {
                for(int j=0;j<w;j++){
                    if(i%2==0){
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }else{
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }
                }
                System.out.printf("\n");
            } {
                for(int j=0;j<w;j++){
                    if(i%2==0){
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }else{
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }
                }
                System.out.printf("\n");
            } for(int j=0;j<w;j++){
                    if(i%2==0){
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }else{
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }
                } int j=0; int j=0; j 0 j<w j w j++ j++ j {
                    if(i%2==0){
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }else{
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }
                } {
                    if(i%2==0){
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }else{
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }
                } if(i%2==0){
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }else{
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    } i%2==0 i%2 i 2 0 {
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    } if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        } j%2==0 j%2 j 2 0 {
                            System.out.
                            printf("#");
                        } System.out.
                            printf("#") System.out.
                            printf System.out System System.out "#" {
                            System.out.printf(".");
                        } System.out.printf(".") System.out.printf System.out System System.out "." {
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    } if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        } j%2==1 j%2 j 2 1 {
                            System.out.
                            printf("#");
                        } System.out.
                            printf("#") System.out.
                            printf System.out System System.out "#" {
                            System.out.printf(".");
                        } System.out.printf(".") System.out.printf System.out System System.out "." System.out.printf("\n") System.out.printf System.out System System.out "\n" h=sc.nextInt() h sc.nextInt() sc.nextInt sc w=sc.nextInt() w sc.nextInt() sc.nextInt sc 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 h=sc.nextInt();
        int w=sc.nextInt();
        while(h!=0 || w!=0){
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    if(i%2==0){
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }else{
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }
                }
                System.out.printf("\n");
            }
            h=sc.nextInt();
            w=sc.nextInt();
            System.out.printf("\n");
        }
        sc.close();

    }
} public class Main{
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        int h=sc.nextInt();
        int w=sc.nextInt();
        while(h!=0 || w!=0){
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    if(i%2==0){
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }else{
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }
                }
                System.out.printf("\n");
            }
            h=sc.nextInt();
            w=sc.nextInt();
            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 h=sc.nextInt();
        int w=sc.nextInt();
        while(h!=0 || w!=0){
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    if(i%2==0){
                        if(j%2==0){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }else{
                        if(j%2==1){
                            System.out.
                            printf("#");
                        }else{
                            System.out.printf(".");
                        }
                    }
                }
                System.out.printf("\n");
            }
            h=sc.nextInt();
            w=sc.nextInt();
            System.out.printf("\n");
        }
        sc.close();

    }
}
