

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		StringBuilder sb = new StringBuilder();
		Scanner scan = new Scanner(System.in);
		while(true){
		//Scanner scan = new Scanner(System.in);


		int H = scan.nextInt();
	    int W = scan.nextInt();


	    if(H == 0 && W == 0)break;
	    for(int i = 1;i <= H ;i++){
	    	for(int j = 1;j <= W; j++){
	    		if((i + j)% 2 == 0){

	    			System.out.print("#");
	    		}else{

	    			System.out.print(".");
	    		}

	    	}
	    	System.out.println();

	    }

	    System.out.println();
	   }

	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		StringBuilder sb = new StringBuilder();
		Scanner scan = new Scanner(System.in);
		while(true){
		//Scanner scan = new Scanner(System.in);


		int H = scan.nextInt();
	    int W = scan.nextInt();


	    if(H == 0 && W == 0)break;
	    for(int i = 1;i <= H ;i++){
	    	for(int j = 1;j <= W; j++){
	    		if((i + j)% 2 == 0){

	    			System.out.print("#");
	    		}else{

	    			System.out.print(".");
	    		}

	    	}
	    	System.out.println();

	    }

	    System.out.println();
	   }

	}
} Main public static void main(String[] args) {
		StringBuilder sb = new StringBuilder();
		Scanner scan = new Scanner(System.in);
		while(true){
		//Scanner scan = new Scanner(System.in);


		int H = scan.nextInt();
	    int W = scan.nextInt();


	    if(H == 0 && W == 0)break;
	    for(int i = 1;i <= H ;i++){
	    	for(int j = 1;j <= W; j++){
	    		if((i + j)% 2 == 0){

	    			System.out.print("#");
	    		}else{

	    			System.out.print(".");
	    		}

	    	}
	    	System.out.println();

	    }

	    System.out.println();
	   }

	} main {
		StringBuilder sb = new StringBuilder();
		Scanner scan = new Scanner(System.in);
		while(true){
		//Scanner scan = new Scanner(System.in);


		int H = scan.nextInt();
	    int W = scan.nextInt();


	    if(H == 0 && W == 0)break;
	    for(int i = 1;i <= H ;i++){
	    	for(int j = 1;j <= W; j++){
	    		if((i + j)% 2 == 0){

	    			System.out.print("#");
	    		}else{

	    			System.out.print(".");
	    		}

	    	}
	    	System.out.println();

	    }

	    System.out.println();
	   }

	} StringBuilder sb = new StringBuilder(); sb new StringBuilder() Scanner scan = new Scanner(System.in); scan new Scanner(System.in) while(true){
		//Scanner scan = new Scanner(System.in);


		int H = scan.nextInt();
	    int W = scan.nextInt();


	    if(H == 0 && W == 0)break;
	    for(int i = 1;i <= H ;i++){
	    	for(int j = 1;j <= W; j++){
	    		if((i + j)% 2 == 0){

	    			System.out.print("#");
	    		}else{

	    			System.out.print(".");
	    		}

	    	}
	    	System.out.println();

	    }

	    System.out.println();
	   } true {
		//Scanner scan = new Scanner(System.in);


		int H = scan.nextInt();
	    int W = scan.nextInt();


	    if(H == 0 && W == 0)break;
	    for(int i = 1;i <= H ;i++){
	    	for(int j = 1;j <= W; j++){
	    		if((i + j)% 2 == 0){

	    			System.out.print("#");
	    		}else{

	    			System.out.print(".");
	    		}

	    	}
	    	System.out.println();

	    }

	    System.out.println();
	   } int H = scan.nextInt(); H scan.nextInt() scan.nextInt scan int W = scan.nextInt(); W scan.nextInt() scan.nextInt scan if(H == 0 && W == 0)break; H == 0 && W == 0 H == 0 H 0 W == 0 W 0 break; for(int i = 1;i <= H ;i++){
	    	for(int j = 1;j <= W; j++){
	    		if((i + j)% 2 == 0){

	    			System.out.print("#");
	    		}else{

	    			System.out.print(".");
	    		}

	    	}
	    	System.out.println();

	    } int i = 1; int i = 1; i 1 i <= H i H i++ i++ i {
	    	for(int j = 1;j <= W; j++){
	    		if((i + j)% 2 == 0){

	    			System.out.print("#");
	    		}else{

	    			System.out.print(".");
	    		}

	    	}
	    	System.out.println();

	    } {
	    	for(int j = 1;j <= W; j++){
	    		if((i + j)% 2 == 0){

	    			System.out.print("#");
	    		}else{

	    			System.out.print(".");
	    		}

	    	}
	    	System.out.println();

	    } for(int j = 1;j <= W; j++){
	    		if((i + j)% 2 == 0){

	    			System.out.print("#");
	    		}else{

	    			System.out.print(".");
	    		}

	    	} int j = 1; int j = 1; j 1 j <= W j W j++ j++ j {
	    		if((i + j)% 2 == 0){

	    			System.out.print("#");
	    		}else{

	    			System.out.print(".");
	    		}

	    	} {
	    		if((i + j)% 2 == 0){

	    			System.out.print("#");
	    		}else{

	    			System.out.print(".");
	    		}

	    	} if((i + j)% 2 == 0){

	    			System.out.print("#");
	    		}else{

	    			System.out.print(".");
	    		} (i + j)% 2 == 0 (i + j)% 2 (i + j) i 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 String[] args args public class Main {

	public static void main(String[] args) {
		StringBuilder sb = new StringBuilder();
		Scanner scan = new Scanner(System.in);
		while(true){
		//Scanner scan = new Scanner(System.in);


		int H = scan.nextInt();
	    int W = scan.nextInt();


	    if(H == 0 && W == 0)break;
	    for(int i = 1;i <= H ;i++){
	    	for(int j = 1;j <= W; j++){
	    		if((i + j)% 2 == 0){

	    			System.out.print("#");
	    		}else{

	    			System.out.print(".");
	    		}

	    	}
	    	System.out.println();

	    }

	    System.out.println();
	   }

	}
} public class Main {

	public static void main(String[] args) {
		StringBuilder sb = new StringBuilder();
		Scanner scan = new Scanner(System.in);
		while(true){
		//Scanner scan = new Scanner(System.in);


		int H = scan.nextInt();
	    int W = scan.nextInt();


	    if(H == 0 && W == 0)break;
	    for(int i = 1;i <= H ;i++){
	    	for(int j = 1;j <= W; j++){
	    		if((i + j)% 2 == 0){

	    			System.out.print("#");
	    		}else{

	    			System.out.print(".");
	    		}

	    	}
	    	System.out.println();

	    }

	    System.out.println();
	   }

	}
} Main


import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		StringBuilder sb = new StringBuilder();
		Scanner scan = new Scanner(System.in);
		while(true){
		//Scanner scan = new Scanner(System.in);


		int H = scan.nextInt();
	    int W = scan.nextInt();


	    if(H == 0 && W == 0)break;
	    for(int i = 1;i <= H ;i++){
	    	for(int j = 1;j <= W; j++){
	    		if((i + j)% 2 == 0){

	    			System.out.print("#");
	    		}else{

	    			System.out.print(".");
	    		}

	    	}
	    	System.out.println();

	    }

	    System.out.println();
	   }

	}
}