import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO ?????????????????????????????????????????????
		int H,W;
		
		Scanner scan = new Scanner(System.in);
		while(true)
		{
			H=scan.nextInt();
			W=scan.nextInt();
			if(H==0&&W==0)
				break;
			
			for(int i=0;i<H;i++) {
				
				for(int j=0;j<W;j++) {
					if((i+j)%2==0)
						System.out.printf("#");
					else
						System.out.printf(".");
				}
				
				System.out.printf("\n");
				
			}
			System.out.printf("\n");
			
		}

	}

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

	public static void main(String[] args) {
		// TODO ?????????????????????????????????????????????
		int H,W;
		
		Scanner scan = new Scanner(System.in);
		while(true)
		{
			H=scan.nextInt();
			W=scan.nextInt();
			if(H==0&&W==0)
				break;
			
			for(int i=0;i<H;i++) {
				
				for(int j=0;j<W;j++) {
					if((i+j)%2==0)
						System.out.printf("#");
					else
						System.out.printf(".");
				}
				
				System.out.printf("\n");
				
			}
			System.out.printf("\n");
			
		}

	}

} Main public static void main(String[] args) {
		// TODO ?????????????????????????????????????????????
		int H,W;
		
		Scanner scan = new Scanner(System.in);
		while(true)
		{
			H=scan.nextInt();
			W=scan.nextInt();
			if(H==0&&W==0)
				break;
			
			for(int i=0;i<H;i++) {
				
				for(int j=0;j<W;j++) {
					if((i+j)%2==0)
						System.out.printf("#");
					else
						System.out.printf(".");
				}
				
				System.out.printf("\n");
				
			}
			System.out.printf("\n");
			
		}

	} main {
		// TODO ?????????????????????????????????????????????
		int H,W;
		
		Scanner scan = new Scanner(System.in);
		while(true)
		{
			H=scan.nextInt();
			W=scan.nextInt();
			if(H==0&&W==0)
				break;
			
			for(int i=0;i<H;i++) {
				
				for(int j=0;j<W;j++) {
					if((i+j)%2==0)
						System.out.printf("#");
					else
						System.out.printf(".");
				}
				
				System.out.printf("\n");
				
			}
			System.out.printf("\n");
			
		}

	} int H H W; W Scanner scan = new Scanner(System.in); scan new Scanner(System.in) while(true)
		{
			H=scan.nextInt();
			W=scan.nextInt();
			if(H==0&&W==0)
				break;
			
			for(int i=0;i<H;i++) {
				
				for(int j=0;j<W;j++) {
					if((i+j)%2==0)
						System.out.printf("#");
					else
						System.out.printf(".");
				}
				
				System.out.printf("\n");
				
			}
			System.out.printf("\n");
			
		} true {
			H=scan.nextInt();
			W=scan.nextInt();
			if(H==0&&W==0)
				break;
			
			for(int i=0;i<H;i++) {
				
				for(int j=0;j<W;j++) {
					if((i+j)%2==0)
						System.out.printf("#");
					else
						System.out.printf(".");
				}
				
				System.out.printf("\n");
				
			}
			System.out.printf("\n");
			
		} H=scan.nextInt() H scan.nextInt() scan.nextInt scan 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=0;i<H;i++) {
				
				for(int j=0;j<W;j++) {
					if((i+j)%2==0)
						System.out.printf("#");
					else
						System.out.printf(".");
				}
				
				System.out.printf("\n");
				
			} int i=0; int i=0; i 0 i<H i H i++ i++ i {
				
				for(int j=0;j<W;j++) {
					if((i+j)%2==0)
						System.out.printf("#");
					else
						System.out.printf(".");
				}
				
				System.out.printf("\n");
				
			} {
				
				for(int j=0;j<W;j++) {
					if((i+j)%2==0)
						System.out.printf("#");
					else
						System.out.printf(".");
				}
				
				System.out.printf("\n");
				
			} for(int j=0;j<W;j++) {
					if((i+j)%2==0)
						System.out.printf("#");
					else
						System.out.printf(".");
				} int j=0; int j=0; j 0 j<W j W j++ j++ j {
					if((i+j)%2==0)
						System.out.printf("#");
					else
						System.out.printf(".");
				} {
					if((i+j)%2==0)
						System.out.printf("#");
					else
						System.out.printf(".");
				} if((i+j)%2==0)
						System.out.printf("#");
					else
						System.out.printf("."); (i+j)%2==0 (i+j)%2 (i+j) i j 2 0 System.out.printf("#") System.out.printf System.out System System.out "#" System.out.printf(".") System.out.printf System.out System System.out "." System.out.printf("\n") System.out.printf System.out System System.out "\n" System.out.printf("\n") System.out.printf System.out System System.out "\n" String[] args args public class Main {

	public static void main(String[] args) {
		// TODO ?????????????????????????????????????????????
		int H,W;
		
		Scanner scan = new Scanner(System.in);
		while(true)
		{
			H=scan.nextInt();
			W=scan.nextInt();
			if(H==0&&W==0)
				break;
			
			for(int i=0;i<H;i++) {
				
				for(int j=0;j<W;j++) {
					if((i+j)%2==0)
						System.out.printf("#");
					else
						System.out.printf(".");
				}
				
				System.out.printf("\n");
				
			}
			System.out.printf("\n");
			
		}

	}

} public class Main {

	public static void main(String[] args) {
		// TODO ?????????????????????????????????????????????
		int H,W;
		
		Scanner scan = new Scanner(System.in);
		while(true)
		{
			H=scan.nextInt();
			W=scan.nextInt();
			if(H==0&&W==0)
				break;
			
			for(int i=0;i<H;i++) {
				
				for(int j=0;j<W;j++) {
					if((i+j)%2==0)
						System.out.printf("#");
					else
						System.out.printf(".");
				}
				
				System.out.printf("\n");
				
			}
			System.out.printf("\n");
			
		}

	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO ?????????????????????????????????????????????
		int H,W;
		
		Scanner scan = new Scanner(System.in);
		while(true)
		{
			H=scan.nextInt();
			W=scan.nextInt();
			if(H==0&&W==0)
				break;
			
			for(int i=0;i<H;i++) {
				
				for(int j=0;j<W;j++) {
					if((i+j)%2==0)
						System.out.printf("#");
					else
						System.out.printf(".");
				}
				
				System.out.printf("\n");
				
			}
			System.out.printf("\n");
			
		}

	}

}