import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		while (true) {
			int h = scan.nextInt();
			int w = scan.nextInt();
			if (h == 0 && w == 0) {break;}
			for (int i = 1; i <= h; i++) {
				for (int j = 1; j <= w; j++) {
					if ( (i % 2 == 1 && j % 2 == 1)
							|| (i % 2 == 0 && j % 2 == 0) ) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
		}
		System.out.print(sb);
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		while (true) {
			int h = scan.nextInt();
			int w = scan.nextInt();
			if (h == 0 && w == 0) {break;}
			for (int i = 1; i <= h; i++) {
				for (int j = 1; j <= w; j++) {
					if ( (i % 2 == 1 && j % 2 == 1)
							|| (i % 2 == 0 && 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) {
		Scanner scan = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		while (true) {
			int h = scan.nextInt();
			int w = scan.nextInt();
			if (h == 0 && w == 0) {break;}
			for (int i = 1; i <= h; i++) {
				for (int j = 1; j <= w; j++) {
					if ( (i % 2 == 1 && j % 2 == 1)
							|| (i % 2 == 0 && j % 2 == 0) ) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
		}
		System.out.print(sb);
	} main {
		Scanner scan = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		while (true) {
			int h = scan.nextInt();
			int w = scan.nextInt();
			if (h == 0 && w == 0) {break;}
			for (int i = 1; i <= h; i++) {
				for (int j = 1; j <= w; j++) {
					if ( (i % 2 == 1 && j % 2 == 1)
							|| (i % 2 == 0 && j % 2 == 0) ) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
		}
		System.out.print(sb);
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) StringBuilder sb = new StringBuilder(); sb new StringBuilder() while (true) {
			int h = scan.nextInt();
			int w = scan.nextInt();
			if (h == 0 && w == 0) {break;}
			for (int i = 1; i <= h; i++) {
				for (int j = 1; j <= w; j++) {
					if ( (i % 2 == 1 && j % 2 == 1)
							|| (i % 2 == 0 && j % 2 == 0) ) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
		} true {
			int h = scan.nextInt();
			int w = scan.nextInt();
			if (h == 0 && w == 0) {break;}
			for (int i = 1; i <= h; i++) {
				for (int j = 1; j <= w; j++) {
					if ( (i % 2 == 1 && j % 2 == 1)
							|| (i % 2 == 0 && j % 2 == 0) ) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
		} int h = scan.nextInt(); h scan.nextInt() scan.nextInt scan int w = scan.nextInt(); w scan.nextInt() scan.nextInt scan if (h == 0 && w == 0) {break;} h == 0 && w == 0 h == 0 h 0 w == 0 w 0 {break;} break; for (int i = 1; i <= h; i++) {
				for (int j = 1; j <= w; j++) {
					if ( (i % 2 == 1 && j % 2 == 1)
							|| (i % 2 == 0 && j % 2 == 0) ) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.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 && j % 2 == 1)
							|| (i % 2 == 0 && j % 2 == 0) ) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			} {
				for (int j = 1; j <= w; j++) {
					if ( (i % 2 == 1 && j % 2 == 1)
							|| (i % 2 == 0 && j % 2 == 0) ) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			} for (int j = 1; j <= w; j++) {
					if ( (i % 2 == 1 && j % 2 == 1)
							|| (i % 2 == 0 && j % 2 == 0) ) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				} int j = 1; int j = 1; j 1 j <= w j w j++ j++ j {
					if ( (i % 2 == 1 && j % 2 == 1)
							|| (i % 2 == 0 && j % 2 == 0) ) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				} {
					if ( (i % 2 == 1 && j % 2 == 1)
							|| (i % 2 == 0 && j % 2 == 0) ) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				} if ( (i % 2 == 1 && j % 2 == 1)
							|| (i % 2 == 0 && j % 2 == 0) ) {
						sb.append("#");
					} else {
						sb.append(".");
					} (i % 2 == 1 && j % 2 == 1)
							|| (i % 2 == 0 && j % 2 == 0) (i % 2 == 1 && j % 2 == 1) i % 2 == 1 i % 2 i 2 1 j % 2 == 1 j % 2 j 2 1 (i % 2 == 0 && j % 2 == 0) i % 2 == 0 i % 2 i 2 0 j % 2 == 0 j % 2 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) {
		Scanner scan = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		while (true) {
			int h = scan.nextInt();
			int w = scan.nextInt();
			if (h == 0 && w == 0) {break;}
			for (int i = 1; i <= h; i++) {
				for (int j = 1; j <= w; j++) {
					if ( (i % 2 == 1 && j % 2 == 1)
							|| (i % 2 == 0 && 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) {
		Scanner scan = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		while (true) {
			int h = scan.nextInt();
			int w = scan.nextInt();
			if (h == 0 && w == 0) {break;}
			for (int i = 1; i <= h; i++) {
				for (int j = 1; j <= w; j++) {
					if ( (i % 2 == 1 && j % 2 == 1)
							|| (i % 2 == 0 && j % 2 == 0) ) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
		}
		System.out.print(sb);
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		while (true) {
			int h = scan.nextInt();
			int w = scan.nextInt();
			if (h == 0 && w == 0) {break;}
			for (int i = 1; i <= h; i++) {
				for (int j = 1; j <= w; j++) {
					if ( (i % 2 == 1 && j % 2 == 1)
							|| (i % 2 == 0 && j % 2 == 0) ) {
						sb.append("#");
					} else {
						sb.append(".");
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
		}
		System.out.print(sb);
	}
}