import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while(true){
            int H= scanner.nextInt();
            int W= scanner.nextInt();
            System.out.print("\n");
            for(int i=0;i<H;i++){
                for(int j=0;j<W;j++){
                    if((j+i)%2==0) System.out.print("#");
                    else System.out.print(".");
                }
                System.out.print("\n");
            }
        }
    }
}
