import java.util.ArrayList;
import java.util.Scanner;
public class PrintChessBoard {
private static Scanner sc = new Scanner(System.in);
private static ArrayList<Integer> height = new ArrayList<Integer>();
private static ArrayList<Integer> width = new ArrayList<Integer>();
public static void main(String[] args) {
getInput();
drawAllRectangle();
}
private static void getInput() {
//"0 0"が入力されるまで入力を受け取る
while(sc.hasNextLine()){
int h = sc.nextInt();
int w = sc.nextInt();
if(! ((h == 0) && (w == 0)) ){
height.add(h);
width.add(w);
}
else{
break;
}
}
}
private static String selectLetter(boolean flag){
if(flag){
return "#";
}
else{
return ".";
}
}
private static void drawRectangle(int index){
int h = height.get(index);
int w = width.get(index);
boolean isPound = true;
int line = 0;
for(int i = 0; i < h; i++){
for(int j = 0; j < w; j++){
System.out.printf(selectLetter(isPound));
isPound = !(isPound);
}
System.out.println();
if( ((++line) % 2) == 1){
isPound = false;
}
}
System.out.println();
}
private static void drawAllRectangle(){
//高さと幅の入力された数が同じなら図形を出力する
int sumRectangle = height.size();
if(sumRectangle == width.size()){
for(int i = 0; i < sumRectangle; i++){
drawRectangle(i);
}
}
else{
System.out.println("高さと幅の入力された数が異なります");
}
}
}