import java.io.*;

class Main{
    public static void main(String[] args) throws Exception{

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int num = 0;

       while(true){

            String num1 = br.readLine();
            String[] num2 = num1.split(" ");
            int H = Integer.parseInt(num2[0]);
            int W = Integer.parseInt(num2[1]);

            if(H == 0 && W == 0){
                break;
            }

            for(int i=0; i<H; i++){
                for(int j=0; j<W; j++){
                    if((i+j)%2 == 0){
                        System.out.print("#");
                    }else {
                        System.out.print(".");
                    }
                }
                    System.out.println("");
            }
            System.out.println("");
        }
    }
} import java.io.*; io.* java class Main{
    public static void main(String[] args) throws Exception{

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int num = 0;

       while(true){

            String num1 = br.readLine();
            String[] num2 = num1.split(" ");
            int H = Integer.parseInt(num2[0]);
            int W = Integer.parseInt(num2[1]);

            if(H == 0 && W == 0){
                break;
            }

            for(int i=0; i<H; i++){
                for(int j=0; j<W; j++){
                    if((i+j)%2 == 0){
                        System.out.print("#");
                    }else {
                        System.out.print(".");
                    }
                }
                    System.out.println("");
            }
            System.out.println("");
        }
    }
} Main public static void main(String[] args) throws Exception{

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int num = 0;

       while(true){

            String num1 = br.readLine();
            String[] num2 = num1.split(" ");
            int H = Integer.parseInt(num2[0]);
            int W = Integer.parseInt(num2[1]);

            if(H == 0 && W == 0){
                break;
            }

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

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int num = 0;

       while(true){

            String num1 = br.readLine();
            String[] num2 = num1.split(" ");
            int H = Integer.parseInt(num2[0]);
            int W = Integer.parseInt(num2[1]);

            if(H == 0 && W == 0){
                break;
            }

            for(int i=0; i<H; i++){
                for(int j=0; j<W; j++){
                    if((i+j)%2 == 0){
                        System.out.print("#");
                    }else {
                        System.out.print(".");
                    }
                }
                    System.out.println("");
            }
            System.out.println("");
        }
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) int num = 0; num 0 while(true){

            String num1 = br.readLine();
            String[] num2 = num1.split(" ");
            int H = Integer.parseInt(num2[0]);
            int W = Integer.parseInt(num2[1]);

            if(H == 0 && W == 0){
                break;
            }

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

            String num1 = br.readLine();
            String[] num2 = num1.split(" ");
            int H = Integer.parseInt(num2[0]);
            int W = Integer.parseInt(num2[1]);

            if(H == 0 && W == 0){
                break;
            }

            for(int i=0; i<H; i++){
                for(int j=0; j<W; j++){
                    if((i+j)%2 == 0){
                        System.out.print("#");
                    }else {
                        System.out.print(".");
                    }
                }
                    System.out.println("");
            }
            System.out.println("");
        } String num1 = br.readLine(); num1 br.readLine() br.readLine br String[] num2 = num1.split(" "); num2 num1.split(" ") num1.split num1 " " int H = Integer.parseInt(num2[0]); H Integer.parseInt(num2[0]) Integer.parseInt Integer num2[0] num2 0 int W = Integer.parseInt(num2[1]); W Integer.parseInt(num2[1]) Integer.parseInt Integer num2[1] num2 1 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++){
                for(int j=0; j<W; j++){
                    if((i+j)%2 == 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++){
                    if((i+j)%2 == 0){
                        System.out.print("#");
                    }else {
                        System.out.print(".");
                    }
                }
                    System.out.println("");
            } {
                for(int j=0; j<W; j++){
                    if((i+j)%2 == 0){
                        System.out.print("#");
                    }else {
                        System.out.print(".");
                    }
                }
                    System.out.println("");
            } for(int j=0; j<W; j++){
                    if((i+j)%2 == 0){
                        System.out.print("#");
                    }else {
                        System.out.print(".");
                    }
                } int j=0; int j=0; j 0 j<W j W j++ j++ j {
                    if((i+j)%2 == 0){
                        System.out.print("#");
                    }else {
                        System.out.print(".");
                    }
                } {
                    if((i+j)%2 == 0){
                        System.out.print("#");
                    }else {
                        System.out.print(".");
                    }
                } if((i+j)%2 == 0){
                        System.out.print("#");
                    }else {
                        System.out.print(".");
                    } (i+j)%2 == 0 (i+j)%2 (i+j) i j 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 "." 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
import java.io.*;

class Main{
    public static void main(String[] args) throws Exception{

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int num = 0;

       while(true){

            String num1 = br.readLine();
            String[] num2 = num1.split(" ");
            int H = Integer.parseInt(num2[0]);
            int W = Integer.parseInt(num2[1]);

            if(H == 0 && W == 0){
                break;
            }

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