import java.io.*;
class Main{
public static void main(String[] args)throws IOException{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
boolean i=true;
while(i){
String str=br.readLine();
String[] arr=str.split(" ");
int h=Integer.parseInt(arr[0]);
int w=Integer.parseInt(arr[1]);
if(h==0 && w==0)  i=false;
else{
for(int k=0; k<h; k++){
for(int j=0; j<w; j++){
if(k%2==0){
if(j%2==0) System.out.print("#");
else  System.out.print(".");
}
else{
if(j%2==0) System.out.print(".");
else  System.out.print("#");
}
}
System.out.println();
}
System.out.println();
}
}
br.close();
}
} import java.io.*; io.* java class Main{
public static void main(String[] args)throws IOException{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
boolean i=true;
while(i){
String str=br.readLine();
String[] arr=str.split(" ");
int h=Integer.parseInt(arr[0]);
int w=Integer.parseInt(arr[1]);
if(h==0 && w==0)  i=false;
else{
for(int k=0; k<h; k++){
for(int j=0; j<w; j++){
if(k%2==0){
if(j%2==0) System.out.print("#");
else  System.out.print(".");
}
else{
if(j%2==0) System.out.print(".");
else  System.out.print("#");
}
}
System.out.println();
}
System.out.println();
}
}
br.close();
}
} Main public static void main(String[] args)throws IOException{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
boolean i=true;
while(i){
String str=br.readLine();
String[] arr=str.split(" ");
int h=Integer.parseInt(arr[0]);
int w=Integer.parseInt(arr[1]);
if(h==0 && w==0)  i=false;
else{
for(int k=0; k<h; k++){
for(int j=0; j<w; j++){
if(k%2==0){
if(j%2==0) System.out.print("#");
else  System.out.print(".");
}
else{
if(j%2==0) System.out.print(".");
else  System.out.print("#");
}
}
System.out.println();
}
System.out.println();
}
}
br.close();
} main {
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
boolean i=true;
while(i){
String str=br.readLine();
String[] arr=str.split(" ");
int h=Integer.parseInt(arr[0]);
int w=Integer.parseInt(arr[1]);
if(h==0 && w==0)  i=false;
else{
for(int k=0; k<h; k++){
for(int j=0; j<w; j++){
if(k%2==0){
if(j%2==0) System.out.print("#");
else  System.out.print(".");
}
else{
if(j%2==0) System.out.print(".");
else  System.out.print("#");
}
}
System.out.println();
}
System.out.println();
}
}
br.close();
} BufferedReader br=new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) boolean i=true; i true while(i){
String str=br.readLine();
String[] arr=str.split(" ");
int h=Integer.parseInt(arr[0]);
int w=Integer.parseInt(arr[1]);
if(h==0 && w==0)  i=false;
else{
for(int k=0; k<h; k++){
for(int j=0; j<w; j++){
if(k%2==0){
if(j%2==0) System.out.print("#");
else  System.out.print(".");
}
else{
if(j%2==0) System.out.print(".");
else  System.out.print("#");
}
}
System.out.println();
}
System.out.println();
}
} i {
String str=br.readLine();
String[] arr=str.split(" ");
int h=Integer.parseInt(arr[0]);
int w=Integer.parseInt(arr[1]);
if(h==0 && w==0)  i=false;
else{
for(int k=0; k<h; k++){
for(int j=0; j<w; j++){
if(k%2==0){
if(j%2==0) System.out.print("#");
else  System.out.print(".");
}
else{
if(j%2==0) System.out.print(".");
else  System.out.print("#");
}
}
System.out.println();
}
System.out.println();
}
} String str=br.readLine(); str br.readLine() br.readLine br String[] arr=str.split(" "); arr str.split(" ") str.split str " " int h=Integer.parseInt(arr[0]); h Integer.parseInt(arr[0]) Integer.parseInt Integer arr[0] arr 0 int w=Integer.parseInt(arr[1]); w Integer.parseInt(arr[1]) Integer.parseInt Integer arr[1] arr 1 if(h==0 && w==0)  i=false;
else{
for(int k=0; k<h; k++){
for(int j=0; j<w; j++){
if(k%2==0){
if(j%2==0) System.out.print("#");
else  System.out.print(".");
}
else{
if(j%2==0) System.out.print(".");
else  System.out.print("#");
}
}
System.out.println();
}
System.out.println();
} h==0 && w==0 h==0 h 0 w==0 w 0 i=false i false {
for(int k=0; k<h; k++){
for(int j=0; j<w; j++){
if(k%2==0){
if(j%2==0) System.out.print("#");
else  System.out.print(".");
}
else{
if(j%2==0) System.out.print(".");
else  System.out.print("#");
}
}
System.out.println();
}
System.out.println();
} for(int k=0; k<h; k++){
for(int j=0; j<w; j++){
if(k%2==0){
if(j%2==0) System.out.print("#");
else  System.out.print(".");
}
else{
if(j%2==0) System.out.print(".");
else  System.out.print("#");
}
}
System.out.println();
} int k=0; int k=0; k 0 k<h k h k++ k++ k {
for(int j=0; j<w; j++){
if(k%2==0){
if(j%2==0) System.out.print("#");
else  System.out.print(".");
}
else{
if(j%2==0) System.out.print(".");
else  System.out.print("#");
}
}
System.out.println();
} {
for(int j=0; j<w; j++){
if(k%2==0){
if(j%2==0) System.out.print("#");
else  System.out.print(".");
}
else{
if(j%2==0) System.out.print(".");
else  System.out.print("#");
}
}
System.out.println();
} for(int j=0; j<w; j++){
if(k%2==0){
if(j%2==0) System.out.print("#");
else  System.out.print(".");
}
else{
if(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(k%2==0){
if(j%2==0) System.out.print("#");
else  System.out.print(".");
}
else{
if(j%2==0) System.out.print(".");
else  System.out.print("#");
}
} {
if(k%2==0){
if(j%2==0) System.out.print("#");
else  System.out.print(".");
}
else{
if(j%2==0) System.out.print(".");
else  System.out.print("#");
}
} if(k%2==0){
if(j%2==0) System.out.print("#");
else  System.out.print(".");
}
else{
if(j%2==0) System.out.print(".");
else  System.out.print("#");
} k%2==0 k%2 k 2 0 {
if(j%2==0) System.out.print("#");
else  System.out.print(".");
} if(j%2==0) System.out.print("#");
else  System.out.print("."); j%2==0 j%2 j 2 0 System.out.print("#") System.out.print System.out System System.out "#" System.out.print(".") System.out.print System.out System System.out "." {
if(j%2==0) System.out.print(".");
else  System.out.print("#");
} if(j%2==0) System.out.print(".");
else  System.out.print("#"); j%2==0 j%2 j 2 0 System.out.print(".") System.out.print System.out System System.out "." 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 br.close() br.close br String[] args args
import java.io.*;
class Main{
public static void main(String[] args)throws IOException{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
boolean i=true;
while(i){
String str=br.readLine();
String[] arr=str.split(" ");
int h=Integer.parseInt(arr[0]);
int w=Integer.parseInt(arr[1]);
if(h==0 && w==0)  i=false;
else{
for(int k=0; k<h; k++){
for(int j=0; j<w; j++){
if(k%2==0){
if(j%2==0) System.out.print("#");
else  System.out.print(".");
}
else{
if(j%2==0) System.out.print(".");
else  System.out.print("#");
}
}
System.out.println();
}
System.out.println();
}
}
br.close();
}
}