import java.util.Scanner;

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

class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int H = sc.nextInt();
		int W = sc.nextInt();
		while(H!=0&&W!=0){
			for(int i=0;i<H;i++){
				for(int j=0;j<W;j++){
					if(i%2==0){
						if(j%2==0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
					}else{
						if(j%2==0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
			H = sc.nextInt();
			W = sc.nextInt();
		}
	}
}