import java.util.Scanner; 
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int h ;
        int w ;
        int t ;
        int y ;
        while(true){
            h = sc.nextInt();
            w = sc.nextInt();
            if(h==0&&w==0)break;
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    t=i%2;
                    y=j%2;
                    if(t!=0&&y==0||y!=0&&t==0){
                        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);
        int h ;
        int w ;
        int t ;
        int y ;
        while(true){
            h = sc.nextInt();
            w = sc.nextInt();
            if(h==0&&w==0)break;
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    t=i%2;
                    y=j%2;
                    if(t!=0&&y==0||y!=0&&t==0){
                        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);
        int h ;
        int w ;
        int t ;
        int y ;
        while(true){
            h = sc.nextInt();
            w = sc.nextInt();
            if(h==0&&w==0)break;
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    t=i%2;
                    y=j%2;
                    if(t!=0&&y==0||y!=0&&t==0){
                        System.out.print(".");
                    }else{
                        System.out.print("#");   
                    }
                }
                System.out.println(); 
            }
            System.out.println();
        }
    } main {
        Scanner sc = new Scanner(System.in);
        int h ;
        int w ;
        int t ;
        int y ;
        while(true){
            h = sc.nextInt();
            w = sc.nextInt();
            if(h==0&&w==0)break;
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    t=i%2;
                    y=j%2;
                    if(t!=0&&y==0||y!=0&&t==0){
                        System.out.print(".");
                    }else{
                        System.out.print("#");   
                    }
                }
                System.out.println(); 
            }
            System.out.println();
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int h ; h int w ; w int t ; t int y ; y while(true){
            h = sc.nextInt();
            w = sc.nextInt();
            if(h==0&&w==0)break;
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    t=i%2;
                    y=j%2;
                    if(t!=0&&y==0||y!=0&&t==0){
                        System.out.print(".");
                    }else{
                        System.out.print("#");   
                    }
                }
                System.out.println(); 
            }
            System.out.println();
        } true {
            h = sc.nextInt();
            w = sc.nextInt();
            if(h==0&&w==0)break;
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    t=i%2;
                    y=j%2;
                    if(t!=0&&y==0||y!=0&&t==0){
                        System.out.print(".");
                    }else{
                        System.out.print("#");   
                    }
                }
                System.out.println(); 
            }
            System.out.println();
        } h = sc.nextInt() h sc.nextInt() sc.nextInt sc 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=0;i<h;i++){
                for(int j=0;j<w;j++){
                    t=i%2;
                    y=j%2;
                    if(t!=0&&y==0||y!=0&&t==0){
                        System.out.print(".");
                    }else{
                        System.out.print("#");   
                    }
                }
                System.out.println(); 
            } int i=0; int i=0; i 0 i<h i h i++ i++ i {
                for(int j=0;j<w;j++){
                    t=i%2;
                    y=j%2;
                    if(t!=0&&y==0||y!=0&&t==0){
                        System.out.print(".");
                    }else{
                        System.out.print("#");   
                    }
                }
                System.out.println(); 
            } {
                for(int j=0;j<w;j++){
                    t=i%2;
                    y=j%2;
                    if(t!=0&&y==0||y!=0&&t==0){
                        System.out.print(".");
                    }else{
                        System.out.print("#");   
                    }
                }
                System.out.println(); 
            } for(int j=0;j<w;j++){
                    t=i%2;
                    y=j%2;
                    if(t!=0&&y==0||y!=0&&t==0){
                        System.out.print(".");
                    }else{
                        System.out.print("#");   
                    }
                } int j=0; int j=0; j 0 j<w j w j++ j++ j {
                    t=i%2;
                    y=j%2;
                    if(t!=0&&y==0||y!=0&&t==0){
                        System.out.print(".");
                    }else{
                        System.out.print("#");   
                    }
                } {
                    t=i%2;
                    y=j%2;
                    if(t!=0&&y==0||y!=0&&t==0){
                        System.out.print(".");
                    }else{
                        System.out.print("#");   
                    }
                } t=i%2 t i%2 i 2 y=j%2 y j%2 j 2 if(t!=0&&y==0||y!=0&&t==0){
                        System.out.print(".");
                    }else{
                        System.out.print("#");   
                    } t!=0&&y==0||y!=0&&t==0 t!=0&&y==0 t!=0 t 0 y==0 y 0 y!=0&&t==0 y!=0 y 0 t==0 t 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 "#" 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);
        int h ;
        int w ;
        int t ;
        int y ;
        while(true){
            h = sc.nextInt();
            w = sc.nextInt();
            if(h==0&&w==0)break;
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    t=i%2;
                    y=j%2;
                    if(t!=0&&y==0||y!=0&&t==0){
                        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);
        int h ;
        int w ;
        int t ;
        int y ;
        while(true){
            h = sc.nextInt();
            w = sc.nextInt();
            if(h==0&&w==0)break;
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    t=i%2;
                    y=j%2;
                    if(t!=0&&y==0||y!=0&&t==0){
                        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);
        int h ;
        int w ;
        int t ;
        int y ;
        while(true){
            h = sc.nextInt();
            w = sc.nextInt();
            if(h==0&&w==0)break;
            for(int i=0;i<h;i++){
                for(int j=0;j<w;j++){
                    t=i%2;
                    y=j%2;
                    if(t!=0&&y==0||y!=0&&t==0){
                        System.out.print(".");
                    }else{
                        System.out.print("#");   
                    }
                }
                System.out.println(); 
            }
            System.out.println();
        }
    }
}
