import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        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(i % 2 == 1)
                    {
                        if(j % 2 == 1)
                            System.out.print("#");
                        else
                            System.out.print(".");
                    }
                    else
                    {
                        if(j % 2 == 1)
                            System.out.print(".");
                        else
                            System.out.print("#");
                    }
                }
                System.out.println();
            }
            System.out.println();
        }
    }
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz