import java.io.*;

public class Main{
public static void main(String[] args){
try{
 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 StringBuilder sb = new StringBuilder();

	while(true){
	 String[] str = br.readLine().split(" ");
	 int H = Integer.parseInt(str [0]);
	 int W = Integer.parseInt(str [1]);

		if(H == 0 || W == 0){
		 break;
		}else{
			for(int i = 0; i < H; i++){
			 	if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				}
			 	if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				}
			sb.append("\n");
			}
		sb.append("\n");
		}
	}
System.out.print(sb);

}catch(IOException e){
System.out.println(e);
}
}
} import java.io.*; io.* java public class Main{
public static void main(String[] args){
try{
 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 StringBuilder sb = new StringBuilder();

	while(true){
	 String[] str = br.readLine().split(" ");
	 int H = Integer.parseInt(str [0]);
	 int W = Integer.parseInt(str [1]);

		if(H == 0 || W == 0){
		 break;
		}else{
			for(int i = 0; i < H; i++){
			 	if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				}
			 	if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				}
			sb.append("\n");
			}
		sb.append("\n");
		}
	}
System.out.print(sb);

}catch(IOException e){
System.out.println(e);
}
}
} Main public static void main(String[] args){
try{
 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 StringBuilder sb = new StringBuilder();

	while(true){
	 String[] str = br.readLine().split(" ");
	 int H = Integer.parseInt(str [0]);
	 int W = Integer.parseInt(str [1]);

		if(H == 0 || W == 0){
		 break;
		}else{
			for(int i = 0; i < H; i++){
			 	if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				}
			 	if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				}
			sb.append("\n");
			}
		sb.append("\n");
		}
	}
System.out.print(sb);

}catch(IOException e){
System.out.println(e);
}
} main {
try{
 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 StringBuilder sb = new StringBuilder();

	while(true){
	 String[] str = br.readLine().split(" ");
	 int H = Integer.parseInt(str [0]);
	 int W = Integer.parseInt(str [1]);

		if(H == 0 || W == 0){
		 break;
		}else{
			for(int i = 0; i < H; i++){
			 	if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				}
			 	if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				}
			sb.append("\n");
			}
		sb.append("\n");
		}
	}
System.out.print(sb);

}catch(IOException e){
System.out.println(e);
}
} try{
 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 StringBuilder sb = new StringBuilder();

	while(true){
	 String[] str = br.readLine().split(" ");
	 int H = Integer.parseInt(str [0]);
	 int W = Integer.parseInt(str [1]);

		if(H == 0 || W == 0){
		 break;
		}else{
			for(int i = 0; i < H; i++){
			 	if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				}
			 	if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				}
			sb.append("\n");
			}
		sb.append("\n");
		}
	}
System.out.print(sb);

}catch(IOException e){
System.out.println(e);
} catch(IOException e){
System.out.println(e);
} IOException e {
System.out.println(e);
} System.out.println(e) System.out.println System.out System System.out e {
 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 StringBuilder sb = new StringBuilder();

	while(true){
	 String[] str = br.readLine().split(" ");
	 int H = Integer.parseInt(str [0]);
	 int W = Integer.parseInt(str [1]);

		if(H == 0 || W == 0){
		 break;
		}else{
			for(int i = 0; i < H; i++){
			 	if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				}
			 	if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				}
			sb.append("\n");
			}
		sb.append("\n");
		}
	}
System.out.print(sb);

} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) StringBuilder sb = new StringBuilder(); sb new StringBuilder() while(true){
	 String[] str = br.readLine().split(" ");
	 int H = Integer.parseInt(str [0]);
	 int W = Integer.parseInt(str [1]);

		if(H == 0 || W == 0){
		 break;
		}else{
			for(int i = 0; i < H; i++){
			 	if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				}
			 	if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				}
			sb.append("\n");
			}
		sb.append("\n");
		}
	} true {
	 String[] str = br.readLine().split(" ");
	 int H = Integer.parseInt(str [0]);
	 int W = Integer.parseInt(str [1]);

		if(H == 0 || W == 0){
		 break;
		}else{
			for(int i = 0; i < H; i++){
			 	if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				}
			 	if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				}
			sb.append("\n");
			}
		sb.append("\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;
		}else{
			for(int i = 0; i < H; i++){
			 	if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				}
			 	if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				}
			sb.append("\n");
			}
		sb.append("\n");
		} H == 0 || W == 0 H == 0 H 0 W == 0 W 0 {
		 break;
		} break; {
			for(int i = 0; i < H; i++){
			 	if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				}
			 	if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				}
			sb.append("\n");
			}
		sb.append("\n");
		} for(int i = 0; i < H; i++){
			 	if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				}
			 	if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				}
			sb.append("\n");
			} int i = 0; int i = 0; i 0 i < H i H i++ i++ i {
			 	if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				}
			 	if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				}
			sb.append("\n");
			} {
			 	if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				}
			 	if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				}
			sb.append("\n");
			} if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				} i % 2 == 0 i % 2 i 2 0 {
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				} for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					} int n = 0; int n = 0; n 0 n < W n W n++ n++ n {
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					} {
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					} if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						} n % 2 == 0 n % 2 n 2 0 {
						 sb.append("#");
					        } sb.append("#") sb.append sb "#" {
						 sb.append(".");
						} sb.append(".") sb.append sb "." if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				} i % 2 == 1 i % 2 i 2 1 {
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				} for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					} int n = 0; int n = 0; n 0 n < W n W n++ n++ n {
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					} {
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					} if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						} n % 2 == 0 n % 2 n 2 0 {
						 sb.append(".");
					        } sb.append(".") sb.append sb "." {
						 sb.append("#");
						} sb.append("#") sb.append sb "#" sb.append("\n") sb.append sb "\n" sb.append("\n") sb.append sb "\n" System.out.print(sb) System.out.print System.out System System.out sb String[] args args public class Main{
public static void main(String[] args){
try{
 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 StringBuilder sb = new StringBuilder();

	while(true){
	 String[] str = br.readLine().split(" ");
	 int H = Integer.parseInt(str [0]);
	 int W = Integer.parseInt(str [1]);

		if(H == 0 || W == 0){
		 break;
		}else{
			for(int i = 0; i < H; i++){
			 	if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				}
			 	if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				}
			sb.append("\n");
			}
		sb.append("\n");
		}
	}
System.out.print(sb);

}catch(IOException e){
System.out.println(e);
}
}
} public class Main{
public static void main(String[] args){
try{
 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 StringBuilder sb = new StringBuilder();

	while(true){
	 String[] str = br.readLine().split(" ");
	 int H = Integer.parseInt(str [0]);
	 int W = Integer.parseInt(str [1]);

		if(H == 0 || W == 0){
		 break;
		}else{
			for(int i = 0; i < H; i++){
			 	if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				}
			 	if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				}
			sb.append("\n");
			}
		sb.append("\n");
		}
	}
System.out.print(sb);

}catch(IOException e){
System.out.println(e);
}
}
} Main
import java.io.*;

public class Main{
public static void main(String[] args){
try{
 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 StringBuilder sb = new StringBuilder();

	while(true){
	 String[] str = br.readLine().split(" ");
	 int H = Integer.parseInt(str [0]);
	 int W = Integer.parseInt(str [1]);

		if(H == 0 || W == 0){
		 break;
		}else{
			for(int i = 0; i < H; i++){
			 	if(i % 2 == 0){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append("#");
					        }else{
						 sb.append(".");
						}
					}
				}
			 	if(i % 2 == 1){
					for(int n = 0; n < W; n++){
				 	 	if(n % 2 == 0){
						 sb.append(".");
					        }else{
						 sb.append("#");
						}
					}
				}
			sb.append("\n");
			}
		sb.append("\n");
		}
	}
System.out.print(sb);

}catch(IOException e){
System.out.println(e);
}
}
}