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));
		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;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
		}
		System.out.print(sb);
	}
} 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));
		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;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
		}
		System.out.print(sb);
	}
} Main public static void main(String[] args) throws IOException {
		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;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
		}
		System.out.print(sb);
	} main {
		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;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {
					if ((i + j) % 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;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {
					if ((i + j) % 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;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {
					if ((i + j) % 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;
			} H == 0 && W == 0 H == 0 H 0 W == 0 W 0 {
				break;
			} break; for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {
					if ((i + j) % 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 {
				for (int j = 0; j < W; j++) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			} {
				for (int j = 0; j < W; j++) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			} for (int j = 0; j < W; j++) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				} int j = 0; int j = 0; j 0 j < W j W j++ j++ j {
					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("\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) throws IOException {
		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;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
		}
		System.out.print(sb);
	}
} public class Main {
	public static void main(String[] args) throws IOException {
		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;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
		}
		System.out.print(sb);
	}
} 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));
		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;
			}
			for (int i = 0; i < H; i++) {
				for (int j = 0; j < W; j++) {
					if ((i + j) % 2 == 0) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
		}
		System.out.print(sb);
	}
}