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

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		PrintStream out = System.out;
		while (true) {
			String[] str = in.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if (H == 0 && W == 0)
				break;
			StringBuilder sb = new StringBuilder();
			if (300 < H || 300 < W)
				throw new RuntimeException("range oger");
			for (int i = 0; i < H; i += 1) {
				for (int j = 0; j < W; j += 1) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append(System.getProperty("line.separator"));
			}
			out.println(sb);
		}
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.PrintStream; PrintStream java.io public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		PrintStream out = System.out;
		while (true) {
			String[] str = in.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if (H == 0 && W == 0)
				break;
			StringBuilder sb = new StringBuilder();
			if (300 < H || 300 < W)
				throw new RuntimeException("range oger");
			for (int i = 0; i < H; i += 1) {
				for (int j = 0; j < W; j += 1) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append(System.getProperty("line.separator"));
			}
			out.println(sb);
		}
	}
} Main public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		PrintStream out = System.out;
		while (true) {
			String[] str = in.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if (H == 0 && W == 0)
				break;
			StringBuilder sb = new StringBuilder();
			if (300 < H || 300 < W)
				throw new RuntimeException("range oger");
			for (int i = 0; i < H; i += 1) {
				for (int j = 0; j < W; j += 1) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append(System.getProperty("line.separator"));
			}
			out.println(sb);
		}
	} main {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		PrintStream out = System.out;
		while (true) {
			String[] str = in.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if (H == 0 && W == 0)
				break;
			StringBuilder sb = new StringBuilder();
			if (300 < H || 300 < W)
				throw new RuntimeException("range oger");
			for (int i = 0; i < H; i += 1) {
				for (int j = 0; j < W; j += 1) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append(System.getProperty("line.separator"));
			}
			out.println(sb);
		}
	} BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); in new BufferedReader(new InputStreamReader(System.in)) PrintStream out = System.out; out System.out System System.out while (true) {
			String[] str = in.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if (H == 0 && W == 0)
				break;
			StringBuilder sb = new StringBuilder();
			if (300 < H || 300 < W)
				throw new RuntimeException("range oger");
			for (int i = 0; i < H; i += 1) {
				for (int j = 0; j < W; j += 1) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append(System.getProperty("line.separator"));
			}
			out.println(sb);
		} true {
			String[] str = in.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if (H == 0 && W == 0)
				break;
			StringBuilder sb = new StringBuilder();
			if (300 < H || 300 < W)
				throw new RuntimeException("range oger");
			for (int i = 0; i < H; i += 1) {
				for (int j = 0; j < W; j += 1) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append(System.getProperty("line.separator"));
			}
			out.println(sb);
		} String[] str = in.readLine().split(" "); str in.readLine().split(" ") in.readLine().split in.readLine() in.readLine in " " 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; StringBuilder sb = new StringBuilder(); sb new StringBuilder() if (300 < H || 300 < W)
				throw new RuntimeException("range oger"); 300 < H || 300 < W 300 < H 300 H 300 < W 300 W throw new RuntimeException("range oger"); new RuntimeException("range oger") for (int i = 0; i < H; i += 1) {
				for (int j = 0; j < W; j += 1) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append(System.getProperty("line.separator"));
			} int i = 0; int i = 0; i 0 i < H i H i += 1 i += 1 i 1 {
				for (int j = 0; j < W; j += 1) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append(System.getProperty("line.separator"));
			} {
				for (int j = 0; j < W; j += 1) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append(System.getProperty("line.separator"));
			} for (int j = 0; j < W; j += 1) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				} int j = 0; int j = 0; j 0 j < W j W j += 1 j += 1 j 1 {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				} {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				} if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					} (i + j) % 2 == 0 (i + j) % 2 (i + j) i j 2 0 {
						sb.append("#");
					} sb.append("#") sb.append sb "#" {
						sb.append(".");
					} sb.append(".") sb.append sb "." sb.append(System.getProperty("line.separator")) sb.append sb System.getProperty("line.separator") System.getProperty System "line.separator" out.println(sb) out.println out sb String[] args args public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		PrintStream out = System.out;
		while (true) {
			String[] str = in.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if (H == 0 && W == 0)
				break;
			StringBuilder sb = new StringBuilder();
			if (300 < H || 300 < W)
				throw new RuntimeException("range oger");
			for (int i = 0; i < H; i += 1) {
				for (int j = 0; j < W; j += 1) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append(System.getProperty("line.separator"));
			}
			out.println(sb);
		}
	}
} public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		PrintStream out = System.out;
		while (true) {
			String[] str = in.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if (H == 0 && W == 0)
				break;
			StringBuilder sb = new StringBuilder();
			if (300 < H || 300 < W)
				throw new RuntimeException("range oger");
			for (int i = 0; i < H; i += 1) {
				for (int j = 0; j < W; j += 1) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append(System.getProperty("line.separator"));
			}
			out.println(sb);
		}
	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		PrintStream out = System.out;
		while (true) {
			String[] str = in.readLine().split(" ");
			int H = Integer.parseInt(str[0]);
			int W = Integer.parseInt(str[1]);
			if (H == 0 && W == 0)
				break;
			StringBuilder sb = new StringBuilder();
			if (300 < H || 300 < W)
				throw new RuntimeException("range oger");
			for (int i = 0; i < H; i += 1) {
				for (int j = 0; j < W; j += 1) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append(System.getProperty("line.separator"));
			}
			out.println(sb);
		}
	}
}