import java.io.*;
import java.util.*;

class Main{
    public static void main(String args[])throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int i;
        int j;
        while(true){
            //String s = br.readLine();
            String[] str = br.readLine().split(" ");
            int h = Integer.parseInt(str[0]);
            int w = Integer.parseInt(str[1]);
            if(h == 0 || w == 0) break;
            for(i=0;i<h; i++){
                System.out.print("");
                for(j=0; j<w-1; j++){
                    if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                        System.out.print(".");
                    }else /*if((i%2==0 && j%2!=0) ^ ())*/{
                        System.out.print("#");
                    }
                   
                }
                if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                    System.out.println(".");
                }else{
                    System.out.println("#");
                }
                //int sum = i + j;
                //System.out.println(sum);
            }
            System.out.print("\n");
        }
    }
} import java.io.*; io.* java import java.util.*; util.* java class Main{
    public static void main(String args[])throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int i;
        int j;
        while(true){
            //String s = br.readLine();
            String[] str = br.readLine().split(" ");
            int h = Integer.parseInt(str[0]);
            int w = Integer.parseInt(str[1]);
            if(h == 0 || w == 0) break;
            for(i=0;i<h; i++){
                System.out.print("");
                for(j=0; j<w-1; j++){
                    if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                        System.out.print(".");
                    }else /*if((i%2==0 && j%2!=0) ^ ())*/{
                        System.out.print("#");
                    }
                   
                }
                if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                    System.out.println(".");
                }else{
                    System.out.println("#");
                }
                //int sum = i + j;
                //System.out.println(sum);
            }
            System.out.print("\n");
        }
    }
} Main public static void main(String args[])throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int i;
        int j;
        while(true){
            //String s = br.readLine();
            String[] str = br.readLine().split(" ");
            int h = Integer.parseInt(str[0]);
            int w = Integer.parseInt(str[1]);
            if(h == 0 || w == 0) break;
            for(i=0;i<h; i++){
                System.out.print("");
                for(j=0; j<w-1; j++){
                    if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                        System.out.print(".");
                    }else /*if((i%2==0 && j%2!=0) ^ ())*/{
                        System.out.print("#");
                    }
                   
                }
                if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                    System.out.println(".");
                }else{
                    System.out.println("#");
                }
                //int sum = i + j;
                //System.out.println(sum);
            }
            System.out.print("\n");
        }
    } main {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int i;
        int j;
        while(true){
            //String s = br.readLine();
            String[] str = br.readLine().split(" ");
            int h = Integer.parseInt(str[0]);
            int w = Integer.parseInt(str[1]);
            if(h == 0 || w == 0) break;
            for(i=0;i<h; i++){
                System.out.print("");
                for(j=0; j<w-1; j++){
                    if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                        System.out.print(".");
                    }else /*if((i%2==0 && j%2!=0) ^ ())*/{
                        System.out.print("#");
                    }
                   
                }
                if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                    System.out.println(".");
                }else{
                    System.out.println("#");
                }
                //int sum = i + j;
                //System.out.println(sum);
            }
            System.out.print("\n");
        }
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) int i; i int j; j while(true){
            //String s = br.readLine();
            String[] str = br.readLine().split(" ");
            int h = Integer.parseInt(str[0]);
            int w = Integer.parseInt(str[1]);
            if(h == 0 || w == 0) break;
            for(i=0;i<h; i++){
                System.out.print("");
                for(j=0; j<w-1; j++){
                    if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                        System.out.print(".");
                    }else /*if((i%2==0 && j%2!=0) ^ ())*/{
                        System.out.print("#");
                    }
                   
                }
                if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                    System.out.println(".");
                }else{
                    System.out.println("#");
                }
                //int sum = i + j;
                //System.out.println(sum);
            }
            System.out.print("\n");
        } true {
            //String s = br.readLine();
            String[] str = br.readLine().split(" ");
            int h = Integer.parseInt(str[0]);
            int w = Integer.parseInt(str[1]);
            if(h == 0 || w == 0) break;
            for(i=0;i<h; i++){
                System.out.print("");
                for(j=0; j<w-1; j++){
                    if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                        System.out.print(".");
                    }else /*if((i%2==0 && j%2!=0) ^ ())*/{
                        System.out.print("#");
                    }
                   
                }
                if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                    System.out.println(".");
                }else{
                    System.out.println("#");
                }
                //int sum = i + j;
                //System.out.println(sum);
            }
            System.out.print("\n");
        } String[] str = br.readLine().split(" "); str br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " int h = Integer.parseInt(str[0]); h Integer.parseInt(str[0]) Integer.parseInt Integer str[0] str 0 int w = Integer.parseInt(str[1]); w Integer.parseInt(str[1]) Integer.parseInt Integer str[1] str 1 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++){
                System.out.print("");
                for(j=0; j<w-1; j++){
                    if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                        System.out.print(".");
                    }else /*if((i%2==0 && j%2!=0) ^ ())*/{
                        System.out.print("#");
                    }
                   
                }
                if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                    System.out.println(".");
                }else{
                    System.out.println("#");
                }
                //int sum = i + j;
                //System.out.println(sum);
            } i=0; i=0 i 0 i<h i h i++ i++ i {
                System.out.print("");
                for(j=0; j<w-1; j++){
                    if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                        System.out.print(".");
                    }else /*if((i%2==0 && j%2!=0) ^ ())*/{
                        System.out.print("#");
                    }
                   
                }
                if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                    System.out.println(".");
                }else{
                    System.out.println("#");
                }
                //int sum = i + j;
                //System.out.println(sum);
            } {
                System.out.print("");
                for(j=0; j<w-1; j++){
                    if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                        System.out.print(".");
                    }else /*if((i%2==0 && j%2!=0) ^ ())*/{
                        System.out.print("#");
                    }
                   
                }
                if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                    System.out.println(".");
                }else{
                    System.out.println("#");
                }
                //int sum = i + j;
                //System.out.println(sum);
            } System.out.print("") System.out.print System.out System System.out "" for(j=0; j<w-1; j++){
                    if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                        System.out.print(".");
                    }else /*if((i%2==0 && j%2!=0) ^ ())*/{
                        System.out.print("#");
                    }
                   
                } j=0; j=0 j 0 j<w-1 j w-1 w 1 j++ j++ j {
                    if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                        System.out.print(".");
                    }else /*if((i%2==0 && j%2!=0) ^ ())*/{
                        System.out.print("#");
                    }
                   
                } {
                    if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                        System.out.print(".");
                    }else /*if((i%2==0 && j%2!=0) ^ ())*/{
                        System.out.print("#");
                    }
                   
                } if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                        System.out.print(".");
                    }else /*if((i%2==0 && j%2!=0) ^ ())*/{
                        System.out.print("#");
                    } (i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0) (i%2!=0 && j%2==0) i%2!=0 i%2 i 2 0 j%2==0 j%2 j 2 0 (i%2==0 && j%2!=0) i%2==0 i%2 i 2 0 j%2!=0 j%2 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 "#" if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                    System.out.println(".");
                }else{
                    System.out.println("#");
                } (i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0) (i%2!=0 && j%2==0) i%2!=0 i%2 i 2 0 j%2==0 j%2 j 2 0 (i%2==0 && j%2!=0) i%2==0 i%2 i 2 0 j%2!=0 j%2 j 2 0 {
                    System.out.println(".");
                } System.out.println(".") System.out.println System.out System System.out "." {
                    System.out.println("#");
                } System.out.println("#") System.out.println System.out System System.out "#" System.out.print("\n") System.out.print System.out System System.out "\n" String args[] args
import java.io.*;
import java.util.*;

class Main{
    public static void main(String args[])throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int i;
        int j;
        while(true){
            //String s = br.readLine();
            String[] str = br.readLine().split(" ");
            int h = Integer.parseInt(str[0]);
            int w = Integer.parseInt(str[1]);
            if(h == 0 || w == 0) break;
            for(i=0;i<h; i++){
                System.out.print("");
                for(j=0; j<w-1; j++){
                    if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                        System.out.print(".");
                    }else /*if((i%2==0 && j%2!=0) ^ ())*/{
                        System.out.print("#");
                    }
                   
                }
                if((i%2!=0 && j%2==0) ^ (i%2==0 && j%2!=0)){
                    System.out.println(".");
                }else{
                    System.out.println("#");
                }
                //int sum = i + j;
                //System.out.println(sum);
            }
            System.out.print("\n");
        }
    }
}