import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
boolean check=true;
while (true) {
int H = sc.nextInt();
int W= sc.nextInt();
if (H == 0 && W == 0) {
break;
}
for(int i=1; i<=H;i++){
    for(int j=1; j<=W;j++){
        if(check==true){
            System.out.printf("#");
            check=false;
        }
        else if(check==false){
            System.out.printf(".");
            check=true;
        }
    }
    System.out.printf("\n");
    }
    System.out.printf("\n");}
}
}
