import java.io.*;
public class Main {
	public static void main(String[] args) throws IOException{
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String line = reader.readLine();
			String[] sarray = line.split(" ", -1);
			int H = Integer.parseInt(sarray[0]);
			int W = Integer.parseInt(sarray[1]);
			int n = 0;
			if(H == 0 && W == 0){
				break;
			} else {
				for(int i = 0; i < H; i++){
					if(i % 2 == 0){
						for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} else {
						for(int j = 0; j < W; j++){
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					}
					System.out.println();
				}
				System.out.println();
			}
		}
	}
} import java.io.*; io.* java public class Main {
	public static void main(String[] args) throws IOException{
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String line = reader.readLine();
			String[] sarray = line.split(" ", -1);
			int H = Integer.parseInt(sarray[0]);
			int W = Integer.parseInt(sarray[1]);
			int n = 0;
			if(H == 0 && W == 0){
				break;
			} else {
				for(int i = 0; i < H; i++){
					if(i % 2 == 0){
						for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} else {
						for(int j = 0; j < W; j++){
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					}
					System.out.println();
				}
				System.out.println();
			}
		}
	}
} Main public static void main(String[] args) throws IOException{
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String line = reader.readLine();
			String[] sarray = line.split(" ", -1);
			int H = Integer.parseInt(sarray[0]);
			int W = Integer.parseInt(sarray[1]);
			int n = 0;
			if(H == 0 && W == 0){
				break;
			} else {
				for(int i = 0; i < H; i++){
					if(i % 2 == 0){
						for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} else {
						for(int j = 0; j < W; j++){
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					}
					System.out.println();
				}
				System.out.println();
			}
		}
	} main {
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String line = reader.readLine();
			String[] sarray = line.split(" ", -1);
			int H = Integer.parseInt(sarray[0]);
			int W = Integer.parseInt(sarray[1]);
			int n = 0;
			if(H == 0 && W == 0){
				break;
			} else {
				for(int i = 0; i < H; i++){
					if(i % 2 == 0){
						for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} else {
						for(int j = 0; j < W; j++){
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					}
					System.out.println();
				}
				System.out.println();
			}
		}
	} BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); reader new BufferedReader(new InputStreamReader(System.in)) while(true){
			String line = reader.readLine();
			String[] sarray = line.split(" ", -1);
			int H = Integer.parseInt(sarray[0]);
			int W = Integer.parseInt(sarray[1]);
			int n = 0;
			if(H == 0 && W == 0){
				break;
			} else {
				for(int i = 0; i < H; i++){
					if(i % 2 == 0){
						for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} else {
						for(int j = 0; j < W; j++){
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					}
					System.out.println();
				}
				System.out.println();
			}
		} true {
			String line = reader.readLine();
			String[] sarray = line.split(" ", -1);
			int H = Integer.parseInt(sarray[0]);
			int W = Integer.parseInt(sarray[1]);
			int n = 0;
			if(H == 0 && W == 0){
				break;
			} else {
				for(int i = 0; i < H; i++){
					if(i % 2 == 0){
						for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} else {
						for(int j = 0; j < W; j++){
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					}
					System.out.println();
				}
				System.out.println();
			}
		} String line = reader.readLine(); line reader.readLine() reader.readLine reader String[] sarray = line.split(" ", -1); sarray line.split(" ", -1) line.split line " " -1 1 int H = Integer.parseInt(sarray[0]); H Integer.parseInt(sarray[0]) Integer.parseInt Integer sarray[0] sarray 0 int W = Integer.parseInt(sarray[1]); W Integer.parseInt(sarray[1]) Integer.parseInt Integer sarray[1] sarray 1 int n = 0; n 0 if(H == 0 && W == 0){
				break;
			} else {
				for(int i = 0; i < H; i++){
					if(i % 2 == 0){
						for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} else {
						for(int j = 0; j < W; j++){
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					}
					System.out.println();
				}
				System.out.println();
			} H == 0 && W == 0 H == 0 H 0 W == 0 W 0 {
				break;
			} break; {
				for(int i = 0; i < H; i++){
					if(i % 2 == 0){
						for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} else {
						for(int j = 0; j < W; j++){
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					}
					System.out.println();
				}
				System.out.println();
			} for(int i = 0; i < H; i++){
					if(i % 2 == 0){
						for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} else {
						for(int j = 0; j < W; j++){
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					}
					System.out.println();
				} int i = 0; int i = 0; i 0 i < H i H i++ i++ i {
					if(i % 2 == 0){
						for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} else {
						for(int j = 0; j < W; j++){
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					}
					System.out.println();
				} {
					if(i % 2 == 0){
						for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} else {
						for(int j = 0; j < W; j++){
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					}
					System.out.println();
				} if(i % 2 == 0){
						for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} else {
						for(int j = 0; j < W; j++){
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} i % 2 == 0 i % 2 i 2 0 {
						for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						} int j = 0; int j = 0; j 0 j < W j W j++ j++ j {
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						} {
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						} if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							} j % 2 == 0 j % 2 j 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 j = 0; j < W; j++){
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} for(int j = 0; j < W; j++){
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						} int j = 0; int j = 0; j 0 j < W j W j++ j++ j {
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						} {
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						} if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							} j % 2 == 1 j % 2 j 2 1 {
								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 reader = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String line = reader.readLine();
			String[] sarray = line.split(" ", -1);
			int H = Integer.parseInt(sarray[0]);
			int W = Integer.parseInt(sarray[1]);
			int n = 0;
			if(H == 0 && W == 0){
				break;
			} else {
				for(int i = 0; i < H; i++){
					if(i % 2 == 0){
						for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} else {
						for(int j = 0; j < W; j++){
							if(j % 2 == 1){
								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 reader = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String line = reader.readLine();
			String[] sarray = line.split(" ", -1);
			int H = Integer.parseInt(sarray[0]);
			int W = Integer.parseInt(sarray[1]);
			int n = 0;
			if(H == 0 && W == 0){
				break;
			} else {
				for(int i = 0; i < H; i++){
					if(i % 2 == 0){
						for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} else {
						for(int j = 0; j < W; j++){
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					}
					System.out.println();
				}
				System.out.println();
			}
		}
	}
} Main
import java.io.*;
public class Main {
	public static void main(String[] args) throws IOException{
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		while(true){
			String line = reader.readLine();
			String[] sarray = line.split(" ", -1);
			int H = Integer.parseInt(sarray[0]);
			int W = Integer.parseInt(sarray[1]);
			int n = 0;
			if(H == 0 && W == 0){
				break;
			} else {
				for(int i = 0; i < H; i++){
					if(i % 2 == 0){
						for(int j = 0; j < W; j++){
							if(j % 2 == 0){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					} else {
						for(int j = 0; j < W; j++){
							if(j % 2 == 1){
								System.out.print("#");
							} else {
								System.out.print(".");
							}
						}
					}
					System.out.println();
				}
				System.out.println();
			}
		}
	}
}