import java.util.Scanner;
class Main{
public static void main(String[] args){
Scanner scan=new Scanner(System.in);
while(true){
int A=scan.nextInt();
int B=scan.nextInt();
if(A==0&&B==0)
break;
for(int a=0;a<A;a++){
for(int b=0;b<B;b++){
	if(a%2==0){
	if(b%2==0)
System.out.print("#");
	else
		System.out.print(".");
	}
	else{
		if(b%2==1)
			System.out.print("#");
				else
					System.out.print(".");
				}
}
System.out.println();
}
System.out.println();
}
}
} import java.util.Scanner; Scanner java.util class Main{
public static void main(String[] args){
Scanner scan=new Scanner(System.in);
while(true){
int A=scan.nextInt();
int B=scan.nextInt();
if(A==0&&B==0)
break;
for(int a=0;a<A;a++){
for(int b=0;b<B;b++){
	if(a%2==0){
	if(b%2==0)
System.out.print("#");
	else
		System.out.print(".");
	}
	else{
		if(b%2==1)
			System.out.print("#");
				else
					System.out.print(".");
				}
}
System.out.println();
}
System.out.println();
}
}
} Main public static void main(String[] args){
Scanner scan=new Scanner(System.in);
while(true){
int A=scan.nextInt();
int B=scan.nextInt();
if(A==0&&B==0)
break;
for(int a=0;a<A;a++){
for(int b=0;b<B;b++){
	if(a%2==0){
	if(b%2==0)
System.out.print("#");
	else
		System.out.print(".");
	}
	else{
		if(b%2==1)
			System.out.print("#");
				else
					System.out.print(".");
				}
}
System.out.println();
}
System.out.println();
}
} main {
Scanner scan=new Scanner(System.in);
while(true){
int A=scan.nextInt();
int B=scan.nextInt();
if(A==0&&B==0)
break;
for(int a=0;a<A;a++){
for(int b=0;b<B;b++){
	if(a%2==0){
	if(b%2==0)
System.out.print("#");
	else
		System.out.print(".");
	}
	else{
		if(b%2==1)
			System.out.print("#");
				else
					System.out.print(".");
				}
}
System.out.println();
}
System.out.println();
}
} Scanner scan=new Scanner(System.in); scan new Scanner(System.in) while(true){
int A=scan.nextInt();
int B=scan.nextInt();
if(A==0&&B==0)
break;
for(int a=0;a<A;a++){
for(int b=0;b<B;b++){
	if(a%2==0){
	if(b%2==0)
System.out.print("#");
	else
		System.out.print(".");
	}
	else{
		if(b%2==1)
			System.out.print("#");
				else
					System.out.print(".");
				}
}
System.out.println();
}
System.out.println();
} true {
int A=scan.nextInt();
int B=scan.nextInt();
if(A==0&&B==0)
break;
for(int a=0;a<A;a++){
for(int b=0;b<B;b++){
	if(a%2==0){
	if(b%2==0)
System.out.print("#");
	else
		System.out.print(".");
	}
	else{
		if(b%2==1)
			System.out.print("#");
				else
					System.out.print(".");
				}
}
System.out.println();
}
System.out.println();
} int A=scan.nextInt(); A scan.nextInt() scan.nextInt scan int B=scan.nextInt(); B scan.nextInt() scan.nextInt scan if(A==0&&B==0)
break; A==0&&B==0 A==0 A 0 B==0 B 0 break; for(int a=0;a<A;a++){
for(int b=0;b<B;b++){
	if(a%2==0){
	if(b%2==0)
System.out.print("#");
	else
		System.out.print(".");
	}
	else{
		if(b%2==1)
			System.out.print("#");
				else
					System.out.print(".");
				}
}
System.out.println();
} int a=0; int a=0; a 0 a<A a A a++ a++ a {
for(int b=0;b<B;b++){
	if(a%2==0){
	if(b%2==0)
System.out.print("#");
	else
		System.out.print(".");
	}
	else{
		if(b%2==1)
			System.out.print("#");
				else
					System.out.print(".");
				}
}
System.out.println();
} {
for(int b=0;b<B;b++){
	if(a%2==0){
	if(b%2==0)
System.out.print("#");
	else
		System.out.print(".");
	}
	else{
		if(b%2==1)
			System.out.print("#");
				else
					System.out.print(".");
				}
}
System.out.println();
} for(int b=0;b<B;b++){
	if(a%2==0){
	if(b%2==0)
System.out.print("#");
	else
		System.out.print(".");
	}
	else{
		if(b%2==1)
			System.out.print("#");
				else
					System.out.print(".");
				}
} int b=0; int b=0; b 0 b<B b B b++ b++ b {
	if(a%2==0){
	if(b%2==0)
System.out.print("#");
	else
		System.out.print(".");
	}
	else{
		if(b%2==1)
			System.out.print("#");
				else
					System.out.print(".");
				}
} {
	if(a%2==0){
	if(b%2==0)
System.out.print("#");
	else
		System.out.print(".");
	}
	else{
		if(b%2==1)
			System.out.print("#");
				else
					System.out.print(".");
				}
} if(a%2==0){
	if(b%2==0)
System.out.print("#");
	else
		System.out.print(".");
	}
	else{
		if(b%2==1)
			System.out.print("#");
				else
					System.out.print(".");
				} a%2==0 a%2 a 2 0 {
	if(b%2==0)
System.out.print("#");
	else
		System.out.print(".");
	} if(b%2==0)
System.out.print("#");
	else
		System.out.print("."); b%2==0 b%2 b 2 0 System.out.print("#") System.out.print System.out System System.out "#" System.out.print(".") System.out.print System.out System System.out "." {
		if(b%2==1)
			System.out.print("#");
				else
					System.out.print(".");
				} if(b%2==1)
			System.out.print("#");
				else
					System.out.print("."); b%2==1 b%2 b 2 1 System.out.print("#") System.out.print System.out System System.out "#" 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
import java.util.Scanner;
class Main{
public static void main(String[] args){
Scanner scan=new Scanner(System.in);
while(true){
int A=scan.nextInt();
int B=scan.nextInt();
if(A==0&&B==0)
break;
for(int a=0;a<A;a++){
for(int b=0;b<B;b++){
	if(a%2==0){
	if(b%2==0)
System.out.print("#");
	else
		System.out.print(".");
	}
	else{
		if(b%2==1)
			System.out.print("#");
				else
					System.out.print(".");
				}
}
System.out.println();
}
System.out.println();
}
}
}