import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws Exception {
        // TODO ?????????????????????????????????????????????
        
        boolean first=true;
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            while ((line = br.readLine()) != null) {
            	String[] str=line.split(" ");
            	int x=Integer.parseInt(str[0]);
            	int y=Integer.parseInt(str[1]);

            	if(x==0&&y==0){
            		break;
            	}
            	for(int i=0;i<x;i++){
            		for(int j=0;j<y;j++){
            			if((i+j)%2==0){
            				System.out.print("#");
            			}else{
            				System.out.print(".");
            			}
            		}
            		System.out.println();
            	}
            	System.out.println();
            }
        }
    }

} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {

	public static void main(String[] args) throws Exception {
        // TODO ?????????????????????????????????????????????
        
        boolean first=true;
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            while ((line = br.readLine()) != null) {
            	String[] str=line.split(" ");
            	int x=Integer.parseInt(str[0]);
            	int y=Integer.parseInt(str[1]);

            	if(x==0&&y==0){
            		break;
            	}
            	for(int i=0;i<x;i++){
            		for(int j=0;j<y;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) throws Exception {
        // TODO ?????????????????????????????????????????????
        
        boolean first=true;
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            while ((line = br.readLine()) != null) {
            	String[] str=line.split(" ");
            	int x=Integer.parseInt(str[0]);
            	int y=Integer.parseInt(str[1]);

            	if(x==0&&y==0){
            		break;
            	}
            	for(int i=0;i<x;i++){
            		for(int j=0;j<y;j++){
            			if((i+j)%2==0){
            				System.out.print("#");
            			}else{
            				System.out.print(".");
            			}
            		}
            		System.out.println();
            	}
            	System.out.println();
            }
        }
    } main {
        // TODO ?????????????????????????????????????????????
        
        boolean first=true;
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            while ((line = br.readLine()) != null) {
            	String[] str=line.split(" ");
            	int x=Integer.parseInt(str[0]);
            	int y=Integer.parseInt(str[1]);

            	if(x==0&&y==0){
            		break;
            	}
            	for(int i=0;i<x;i++){
            		for(int j=0;j<y;j++){
            			if((i+j)%2==0){
            				System.out.print("#");
            			}else{
            				System.out.print(".");
            			}
            		}
            		System.out.println();
            	}
            	System.out.println();
            }
        }
    } boolean first=true; first true try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            while ((line = br.readLine()) != null) {
            	String[] str=line.split(" ");
            	int x=Integer.parseInt(str[0]);
            	int y=Integer.parseInt(str[1]);

            	if(x==0&&y==0){
            		break;
            	}
            	for(int i=0;i<x;i++){
            		for(int j=0;j<y;j++){
            			if((i+j)%2==0){
            				System.out.print("#");
            			}else{
            				System.out.print(".");
            			}
            		}
            		System.out.println();
            	}
            	System.out.println();
            }
        } {
            String line;
            while ((line = br.readLine()) != null) {
            	String[] str=line.split(" ");
            	int x=Integer.parseInt(str[0]);
            	int y=Integer.parseInt(str[1]);

            	if(x==0&&y==0){
            		break;
            	}
            	for(int i=0;i<x;i++){
            		for(int j=0;j<y;j++){
            			if((i+j)%2==0){
            				System.out.print("#");
            			}else{
            				System.out.print(".");
            			}
            		}
            		System.out.println();
            	}
            	System.out.println();
            }
        } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)) BufferedReader br = new BufferedReader(new InputStreamReader(System.in)) new BufferedReader(new InputStreamReader(System.in)) String line; line while ((line = br.readLine()) != null) {
            	String[] str=line.split(" ");
            	int x=Integer.parseInt(str[0]);
            	int y=Integer.parseInt(str[1]);

            	if(x==0&&y==0){
            		break;
            	}
            	for(int i=0;i<x;i++){
            		for(int j=0;j<y;j++){
            			if((i+j)%2==0){
            				System.out.print("#");
            			}else{
            				System.out.print(".");
            			}
            		}
            		System.out.println();
            	}
            	System.out.println();
            } (line = br.readLine()) != null (line = br.readLine()) line br.readLine() br.readLine br null {
            	String[] str=line.split(" ");
            	int x=Integer.parseInt(str[0]);
            	int y=Integer.parseInt(str[1]);

            	if(x==0&&y==0){
            		break;
            	}
            	for(int i=0;i<x;i++){
            		for(int j=0;j<y;j++){
            			if((i+j)%2==0){
            				System.out.print("#");
            			}else{
            				System.out.print(".");
            			}
            		}
            		System.out.println();
            	}
            	System.out.println();
            } String[] str=line.split(" "); str line.split(" ") line.split line " " int x=Integer.parseInt(str[0]); x Integer.parseInt(str[0]) Integer.parseInt Integer str[0] str 0 int y=Integer.parseInt(str[1]); y Integer.parseInt(str[1]) Integer.parseInt Integer str[1] str 1 if(x==0&&y==0){
            		break;
            	} x==0&&y==0 x==0 x 0 y==0 y 0 {
            		break;
            	} break; for(int i=0;i<x;i++){
            		for(int j=0;j<y;j++){
            			if((i+j)%2==0){
            				System.out.print("#");
            			}else{
            				System.out.print(".");
            			}
            		}
            		System.out.println();
            	} int i=0; int i=0; i 0 i<x i x i++ i++ i {
            		for(int j=0;j<y;j++){
            			if((i+j)%2==0){
            				System.out.print("#");
            			}else{
            				System.out.print(".");
            			}
            		}
            		System.out.println();
            	} {
            		for(int j=0;j<y;j++){
            			if((i+j)%2==0){
            				System.out.print("#");
            			}else{
            				System.out.print(".");
            			}
            		}
            		System.out.println();
            	} for(int j=0;j<y;j++){
            			if((i+j)%2==0){
            				System.out.print("#");
            			}else{
            				System.out.print(".");
            			}
            		} int j=0; int j=0; j 0 j<y j y 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) throws Exception {
        // TODO ?????????????????????????????????????????????
        
        boolean first=true;
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            while ((line = br.readLine()) != null) {
            	String[] str=line.split(" ");
            	int x=Integer.parseInt(str[0]);
            	int y=Integer.parseInt(str[1]);

            	if(x==0&&y==0){
            		break;
            	}
            	for(int i=0;i<x;i++){
            		for(int j=0;j<y;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) throws Exception {
        // TODO ?????????????????????????????????????????????
        
        boolean first=true;
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            while ((line = br.readLine()) != null) {
            	String[] str=line.split(" ");
            	int x=Integer.parseInt(str[0]);
            	int y=Integer.parseInt(str[1]);

            	if(x==0&&y==0){
            		break;
            	}
            	for(int i=0;i<x;i++){
            		for(int j=0;j<y;j++){
            			if((i+j)%2==0){
            				System.out.print("#");
            			}else{
            				System.out.print(".");
            			}
            		}
            		System.out.println();
            	}
            	System.out.println();
            }
        }
    }

} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws Exception {
        // TODO ?????????????????????????????????????????????
        
        boolean first=true;
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            String line;
            while ((line = br.readLine()) != null) {
            	String[] str=line.split(" ");
            	int x=Integer.parseInt(str[0]);
            	int y=Integer.parseInt(str[1]);

            	if(x==0&&y==0){
            		break;
            	}
            	for(int i=0;i<x;i++){
            		for(int j=0;j<y;j++){
            			if((i+j)%2==0){
            				System.out.print("#");
            			}else{
            				System.out.print(".");
            			}
            		}
            		System.out.println();
            	}
            	System.out.println();
            }
        }
    }

}