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

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

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