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

public class Main {
    public static void main(String[] args) {
        try {
            BufferedReader stdReader = new BufferedReader(new InputStreamReader(System.in));
            
            String line;
            
            while((line = stdReader.readLine()) != null) {
                String[] input = line.split(" ", 0);
                int h = Integer.parseInt(input[0]);
                int w = Integer.parseInt(input[1]);
                
                // h, w?????¨??????0?????¨?????????
                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) {
                            System.out.print("#");
                        } else {
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
            stdReader.close();
        } catch(Exception e) {
            e.getStackTrace();
            System.exit(-1);
        }
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {
    public static void main(String[] args) {
        try {
            BufferedReader stdReader = new BufferedReader(new InputStreamReader(System.in));
            
            String line;
            
            while((line = stdReader.readLine()) != null) {
                String[] input = line.split(" ", 0);
                int h = Integer.parseInt(input[0]);
                int w = Integer.parseInt(input[1]);
                
                // h, w?????¨??????0?????¨?????????
                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) {
                            System.out.print("#");
                        } else {
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
            stdReader.close();
        } catch(Exception e) {
            e.getStackTrace();
            System.exit(-1);
        }
    }
} Main public static void main(String[] args) {
        try {
            BufferedReader stdReader = new BufferedReader(new InputStreamReader(System.in));
            
            String line;
            
            while((line = stdReader.readLine()) != null) {
                String[] input = line.split(" ", 0);
                int h = Integer.parseInt(input[0]);
                int w = Integer.parseInt(input[1]);
                
                // h, w?????¨??????0?????¨?????????
                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) {
                            System.out.print("#");
                        } else {
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
            stdReader.close();
        } catch(Exception e) {
            e.getStackTrace();
            System.exit(-1);
        }
    } main {
        try {
            BufferedReader stdReader = new BufferedReader(new InputStreamReader(System.in));
            
            String line;
            
            while((line = stdReader.readLine()) != null) {
                String[] input = line.split(" ", 0);
                int h = Integer.parseInt(input[0]);
                int w = Integer.parseInt(input[1]);
                
                // h, w?????¨??????0?????¨?????????
                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) {
                            System.out.print("#");
                        } else {
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
            stdReader.close();
        } catch(Exception e) {
            e.getStackTrace();
            System.exit(-1);
        }
    } try {
            BufferedReader stdReader = new BufferedReader(new InputStreamReader(System.in));
            
            String line;
            
            while((line = stdReader.readLine()) != null) {
                String[] input = line.split(" ", 0);
                int h = Integer.parseInt(input[0]);
                int w = Integer.parseInt(input[1]);
                
                // h, w?????¨??????0?????¨?????????
                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) {
                            System.out.print("#");
                        } else {
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
            stdReader.close();
        } catch(Exception e) {
            e.getStackTrace();
            System.exit(-1);
        } catch(Exception e) {
            e.getStackTrace();
            System.exit(-1);
        } Exception e {
            e.getStackTrace();
            System.exit(-1);
        } e.getStackTrace() e.getStackTrace e System.exit(-1) System.exit System -1 1 {
            BufferedReader stdReader = new BufferedReader(new InputStreamReader(System.in));
            
            String line;
            
            while((line = stdReader.readLine()) != null) {
                String[] input = line.split(" ", 0);
                int h = Integer.parseInt(input[0]);
                int w = Integer.parseInt(input[1]);
                
                // h, w?????¨??????0?????¨?????????
                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) {
                            System.out.print("#");
                        } else {
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
            stdReader.close();
        } BufferedReader stdReader = new BufferedReader(new InputStreamReader(System.in)); stdReader new BufferedReader(new InputStreamReader(System.in)) String line; line while((line = stdReader.readLine()) != null) {
                String[] input = line.split(" ", 0);
                int h = Integer.parseInt(input[0]);
                int w = Integer.parseInt(input[1]);
                
                // h, w?????¨??????0?????¨?????????
                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) {
                            System.out.print("#");
                        } else {
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            } (line = stdReader.readLine()) != null (line = stdReader.readLine()) line stdReader.readLine() stdReader.readLine stdReader null {
                String[] input = line.split(" ", 0);
                int h = Integer.parseInt(input[0]);
                int w = Integer.parseInt(input[1]);
                
                // h, w?????¨??????0?????¨?????????
                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) {
                            System.out.print("#");
                        } else {
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            } String[] input = line.split(" ", 0); input line.split(" ", 0) line.split line " " 0 int h = Integer.parseInt(input[0]); h Integer.parseInt(input[0]) Integer.parseInt Integer input[0] input 0 int w = Integer.parseInt(input[1]); w Integer.parseInt(input[1]) Integer.parseInt Integer input[1] input 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) {
                            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 {
                    for(int j = 0; j < w; j++) {
                        if((i + j) % 2 == 0) {
                            System.out.print("#");
                        } else {
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                } {
                    for(int j = 0; j < w; j++) {
                        if((i + j) % 2 == 0) {
                            System.out.print("#");
                        } else {
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                } for(int j = 0; j < w; j++) {
                        if((i + 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((i + j) % 2 == 0) {
                            System.out.print("#");
                        } else {
                            System.out.print(".");
                        }
                    } {
                        if((i + j) % 2 == 0) {
                            System.out.print("#");
                        } else {
                            System.out.print(".");
                        }
                    } if((i + j) % 2 == 0) {
                            System.out.print("#");
                        } else {
                            System.out.print(".");
                        } (i + j) % 2 == 0 (i + j) % 2 (i + j) i 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 "." System.out.println() System.out.println System.out System System.out System.out.println() System.out.println System.out System System.out stdReader.close() stdReader.close stdReader String[] args args public class Main {
    public static void main(String[] args) {
        try {
            BufferedReader stdReader = new BufferedReader(new InputStreamReader(System.in));
            
            String line;
            
            while((line = stdReader.readLine()) != null) {
                String[] input = line.split(" ", 0);
                int h = Integer.parseInt(input[0]);
                int w = Integer.parseInt(input[1]);
                
                // h, w?????¨??????0?????¨?????????
                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) {
                            System.out.print("#");
                        } else {
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
            stdReader.close();
        } catch(Exception e) {
            e.getStackTrace();
            System.exit(-1);
        }
    }
} public class Main {
    public static void main(String[] args) {
        try {
            BufferedReader stdReader = new BufferedReader(new InputStreamReader(System.in));
            
            String line;
            
            while((line = stdReader.readLine()) != null) {
                String[] input = line.split(" ", 0);
                int h = Integer.parseInt(input[0]);
                int w = Integer.parseInt(input[1]);
                
                // h, w?????¨??????0?????¨?????????
                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) {
                            System.out.print("#");
                        } else {
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
            stdReader.close();
        } catch(Exception e) {
            e.getStackTrace();
            System.exit(-1);
        }
    }
} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) {
        try {
            BufferedReader stdReader = new BufferedReader(new InputStreamReader(System.in));
            
            String line;
            
            while((line = stdReader.readLine()) != null) {
                String[] input = line.split(" ", 0);
                int h = Integer.parseInt(input[0]);
                int w = Integer.parseInt(input[1]);
                
                // h, w?????¨??????0?????¨?????????
                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) {
                            System.out.print("#");
                        } else {
                            System.out.print(".");
                        }
                    }
                    System.out.println();
                }
                System.out.println();
            }
            stdReader.close();
        } catch(Exception e) {
            e.getStackTrace();
            System.exit(-1);
        }
    }
}