import java.io.*;
public class Main {
	public static void main(String[] args)throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int count = 0;
		
		while(true){
			//int count= 0;
			
			String[] str = br.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if(H==0 && W==0) break;
			
			
			//if(H%2 == 0){
				for(int i=0; i<H; i++){
					for(int j=0; j<W; j++){
						if((j+i)%2 == 0){
							System.out.print("#");
						}else {
							System.out.print(".");
						}
						
					}
					System.out.print("\n");
			
				}
				System.out.print("\n");
			
					
		}
		
	}
} import java.io.*; io.* java public class Main {
	public static void main(String[] args)throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int count = 0;
		
		while(true){
			//int count= 0;
			
			String[] str = br.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if(H==0 && W==0) break;
			
			
			//if(H%2 == 0){
				for(int i=0; i<H; i++){
					for(int j=0; j<W; j++){
						if((j+i)%2 == 0){
							System.out.print("#");
						}else {
							System.out.print(".");
						}
						
					}
					System.out.print("\n");
			
				}
				System.out.print("\n");
			
					
		}
		
	}
} Main public static void main(String[] args)throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int count = 0;
		
		while(true){
			//int count= 0;
			
			String[] str = br.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if(H==0 && W==0) break;
			
			
			//if(H%2 == 0){
				for(int i=0; i<H; i++){
					for(int j=0; j<W; j++){
						if((j+i)%2 == 0){
							System.out.print("#");
						}else {
							System.out.print(".");
						}
						
					}
					System.out.print("\n");
			
				}
				System.out.print("\n");
			
					
		}
		
	} main {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int count = 0;
		
		while(true){
			//int count= 0;
			
			String[] str = br.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if(H==0 && W==0) break;
			
			
			//if(H%2 == 0){
				for(int i=0; i<H; i++){
					for(int j=0; j<W; j++){
						if((j+i)%2 == 0){
							System.out.print("#");
						}else {
							System.out.print(".");
						}
						
					}
					System.out.print("\n");
			
				}
				System.out.print("\n");
			
					
		}
		
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) int count = 0; count 0 while(true){
			//int count= 0;
			
			String[] str = br.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if(H==0 && W==0) break;
			
			
			//if(H%2 == 0){
				for(int i=0; i<H; i++){
					for(int j=0; j<W; j++){
						if((j+i)%2 == 0){
							System.out.print("#");
						}else {
							System.out.print(".");
						}
						
					}
					System.out.print("\n");
			
				}
				System.out.print("\n");
			
					
		} true {
			//int count= 0;
			
			String[] str = br.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if(H==0 && W==0) break;
			
			
			//if(H%2 == 0){
				for(int i=0; i<H; i++){
					for(int j=0; j<W; j++){
						if((j+i)%2 == 0){
							System.out.print("#");
						}else {
							System.out.print(".");
						}
						
					}
					System.out.print("\n");
			
				}
				System.out.print("\n");
			
					
		} String[] str = br.readLine().split(" "); str br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " int H = Integer.parseInt(str[0]); H Integer.parseInt(str[0]) Integer.parseInt Integer str[0] str 0 int W = Integer.parseInt(str[1]); W Integer.parseInt(str[1]) Integer.parseInt Integer str[1] str 1 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((j+i)%2 == 0){
							System.out.print("#");
						}else {
							System.out.print(".");
						}
						
					}
					System.out.print("\n");
			
				} int i=0; int i=0; i 0 i<H i H i++ i++ i {
					for(int j=0; j<W; j++){
						if((j+i)%2 == 0){
							System.out.print("#");
						}else {
							System.out.print(".");
						}
						
					}
					System.out.print("\n");
			
				} {
					for(int j=0; j<W; j++){
						if((j+i)%2 == 0){
							System.out.print("#");
						}else {
							System.out.print(".");
						}
						
					}
					System.out.print("\n");
			
				} for(int j=0; j<W; j++){
						if((j+i)%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((j+i)%2 == 0){
							System.out.print("#");
						}else {
							System.out.print(".");
						}
						
					} {
						if((j+i)%2 == 0){
							System.out.print("#");
						}else {
							System.out.print(".");
						}
						
					} if((j+i)%2 == 0){
							System.out.print("#");
						}else {
							System.out.print(".");
						} (j+i)%2 == 0 (j+i)%2 (j+i) j i 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.print("\n") System.out.print System.out System System.out "\n" System.out.print("\n") System.out.print System.out System System.out "\n" String[] args args public class Main {
	public static void main(String[] args)throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int count = 0;
		
		while(true){
			//int count= 0;
			
			String[] str = br.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if(H==0 && W==0) break;
			
			
			//if(H%2 == 0){
				for(int i=0; i<H; i++){
					for(int j=0; j<W; j++){
						if((j+i)%2 == 0){
							System.out.print("#");
						}else {
							System.out.print(".");
						}
						
					}
					System.out.print("\n");
			
				}
				System.out.print("\n");
			
					
		}
		
	}
} public class Main {
	public static void main(String[] args)throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int count = 0;
		
		while(true){
			//int count= 0;
			
			String[] str = br.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if(H==0 && W==0) break;
			
			
			//if(H%2 == 0){
				for(int i=0; i<H; i++){
					for(int j=0; j<W; j++){
						if((j+i)%2 == 0){
							System.out.print("#");
						}else {
							System.out.print(".");
						}
						
					}
					System.out.print("\n");
			
				}
				System.out.print("\n");
			
					
		}
		
	}
} Main
import java.io.*;
public class Main {
	public static void main(String[] args)throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int count = 0;
		
		while(true){
			//int count= 0;
			
			String[] str = br.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if(H==0 && W==0) break;
			
			
			//if(H%2 == 0){
				for(int i=0; i<H; i++){
					for(int j=0; j<W; j++){
						if((j+i)%2 == 0){
							System.out.print("#");
						}else {
							System.out.print(".");
						}
						
					}
					System.out.print("\n");
			
				}
				System.out.print("\n");
			
					
		}
		
	}
}