import java.io.*;

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

public class Main{
	public static void main(String[] args)throws IOException, NumberFormatException{
		BufferedReader br = new BufferedReader (new InputStreamReader(System.in));
		StringBuilder builder = new StringBuilder();
		
		while(true){
			String[] s = br.readLine().split(" ");
			int h = Integer.parseInt(s[0]);
			int w = Integer.parseInt(s[1]);
			if( h==0 && w==0 ) break;
			
			// ???????????°?????????
			for( int i=1 ; i<=h ; i++ ){
				// ????????°?????????
				for( int j=1 ; j<=w ; j++ ){
					if( i%2==1 ){
						if( j%2==1 ){					
							builder.append("#");
						}else{
							builder.append(".");
						}
					}else{
						if( j%2==0 ){
							builder.append("#");
						}else{
							builder.append(".");
						}
					}
				}//???
				builder.append("\n");
			}//??????
			builder.append("\n");
		}
		System.out.print(builder);
	}
}