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

public class Main {
	public static void main(String args[]) throws IOException {

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

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		while (true) {
			String str = br.readLine();
			String[] w_h = str.split(" ", 0);
			int h = Integer.parseInt(w_h[0]);
			int w = Integer.parseInt(w_h[1]);
			if (w == 0 && h == 0) {
				break;
			}
			for (int j = 0; j < h; j++) {
				if (j % 2 == 0) {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
				} else {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	}
} Main public static void main(String args[]) throws IOException {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		while (true) {
			String str = br.readLine();
			String[] w_h = str.split(" ", 0);
			int h = Integer.parseInt(w_h[0]);
			int w = Integer.parseInt(w_h[1]);
			if (w == 0 && h == 0) {
				break;
			}
			for (int j = 0; j < h; j++) {
				if (j % 2 == 0) {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
				} else {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	} main {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		while (true) {
			String str = br.readLine();
			String[] w_h = str.split(" ", 0);
			int h = Integer.parseInt(w_h[0]);
			int w = Integer.parseInt(w_h[1]);
			if (w == 0 && h == 0) {
				break;
			}
			for (int j = 0; j < h; j++) {
				if (j % 2 == 0) {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
				} else {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) while (true) {
			String str = br.readLine();
			String[] w_h = str.split(" ", 0);
			int h = Integer.parseInt(w_h[0]);
			int w = Integer.parseInt(w_h[1]);
			if (w == 0 && h == 0) {
				break;
			}
			for (int j = 0; j < h; j++) {
				if (j % 2 == 0) {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
				} else {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		} true {
			String str = br.readLine();
			String[] w_h = str.split(" ", 0);
			int h = Integer.parseInt(w_h[0]);
			int w = Integer.parseInt(w_h[1]);
			if (w == 0 && h == 0) {
				break;
			}
			for (int j = 0; j < h; j++) {
				if (j % 2 == 0) {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
				} else {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		} String str = br.readLine(); str br.readLine() br.readLine br String[] w_h = str.split(" ", 0); w_h str.split(" ", 0) str.split str " " 0 int h = Integer.parseInt(w_h[0]); h Integer.parseInt(w_h[0]) Integer.parseInt Integer w_h[0] w_h 0 int w = Integer.parseInt(w_h[1]); w Integer.parseInt(w_h[1]) Integer.parseInt Integer w_h[1] w_h 1 if (w == 0 && h == 0) {
				break;
			} w == 0 && h == 0 w == 0 w 0 h == 0 h 0 {
				break;
			} break; for (int j = 0; j < h; j++) {
				if (j % 2 == 0) {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
				} else {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			} int j = 0; int j = 0; j 0 j < h j h j++ j++ j {
				if (j % 2 == 0) {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
				} else {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			} {
				if (j % 2 == 0) {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
				} else {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			} if (j % 2 == 0) {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
				} else {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				} j % 2 == 0 j % 2 j 2 0 {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
				} for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} int i = 0; int i = 0; i 0 i < w i w i++ i++ i {
						if (i % 2 == 0) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} {
						if (i % 2 == 0) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} if (i % 2 == 0) {
							System.out.print("#");
						} else {
							System.out.print(".");
						} i % 2 == 0 i % 2 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 "." {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				} for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					} int i = 0; int i = 0; i 0 i < w i w i++ i++ i {
						if (i % 2 == 0) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					} {
						if (i % 2 == 0) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					} if (i % 2 == 0) {
							System.out.print(".");
						} else {
							System.out.print("#");
						} i % 2 == 0 i % 2 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.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 IOException {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		while (true) {
			String str = br.readLine();
			String[] w_h = str.split(" ", 0);
			int h = Integer.parseInt(w_h[0]);
			int w = Integer.parseInt(w_h[1]);
			if (w == 0 && h == 0) {
				break;
			}
			for (int j = 0; j < h; j++) {
				if (j % 2 == 0) {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
				} else {
					for (int i = 0; i < w; i++) {
						if (i % 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 IOException {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		while (true) {
			String str = br.readLine();
			String[] w_h = str.split(" ", 0);
			int h = Integer.parseInt(w_h[0]);
			int w = Integer.parseInt(w_h[1]);
			if (w == 0 && h == 0) {
				break;
			}
			for (int j = 0; j < h; j++) {
				if (j % 2 == 0) {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					}
				} else {
					for (int i = 0; i < w; i++) {
						if (i % 2 == 0) {
							System.out.print(".");
						} else {
							System.out.print("#");
						}
					}
				}
				System.out.println("");
			}
			System.out.println("");
		}
	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
	public static void main(String args[]) throws IOException {

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