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;

            if(H%2 == 0){
                if(W%2 == 0){
                    for(int i=0;i<H/2;i++) {
                        for(int j=0; i < W / 2; j++)
                            System.out.print("#.");
                        System.out.println();
                        for(int j=0;j<W/2;j++)
                            System.out.print(".#");
                        System.out.println();
                    }
                }else{
                    for(int j=0;j<W/2;j++)
                        System.out.print("#.");
                    System.out.println("#");
                    for(int j=0;j<W/2;j++)
                        System.out.print(".#");
                    System.out.println(".");
                }
            }else{
                if(W%2 == 0){
                    for(int i=0;i<H/2;i++){
                        for(int j=0; j < W / 2; j++)
                            System.out.print("#.");
                        System.out.println();
                        for(int j=0;j<W/2;j++)
                            System.out.print(".#");
                        System.out.println();
                    }
                    for(int j=0; j < W / 2; j++)
                        System.out.print("#.");
                    System.out.println();
                }else{
                    for(int i=0;i<H/2;i++) {
                        for (int j = 0; j < W / 2; j++)
                            System.out.print("#.");
                        System.out.println("#");
                        for (int j = 0; j < W / 2; j++)
                            System.out.print(".#");
                        System.out.println(".");
                    }
                    for (int j = 0; j < W / 2; j++)
                        System.out.print("#.");
                    System.out.println("#");
                }
            }
        }
    }
}

