import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int h, w;

        while(true) {
            h = sc.nextInt();
            w = sc.nextInt();
            
            if (h == 0 && w == 0) {
                break;
            }

            StringBuilder sb1 = new StringBuilder();
            StringBuilder sb2 = new StringBuilder();

            for (int i = 0; i < w; i++) {
                if ((i % 2) == 0) {
                    sb1.append("#");
                    sb2.append(".");
                } else {
                    sb1.append(".");
                    sb2.append("#");
                }
            }
            

            for (int j = 0; j < h; j++) {
                if ((j % 2) == 0) {
                    System.out.println(sb1);
                } else {
                    System.out.println(sb2);
                }

            }

            System.out.println();

        }
    }
} import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int h, w;

        while(true) {
            h = sc.nextInt();
            w = sc.nextInt();
            
            if (h == 0 && w == 0) {
                break;
            }

            StringBuilder sb1 = new StringBuilder();
            StringBuilder sb2 = new StringBuilder();

            for (int i = 0; i < w; i++) {
                if ((i % 2) == 0) {
                    sb1.append("#");
                    sb2.append(".");
                } else {
                    sb1.append(".");
                    sb2.append("#");
                }
            }
            

            for (int j = 0; j < h; j++) {
                if ((j % 2) == 0) {
                    System.out.println(sb1);
                } else {
                    System.out.println(sb2);
                }

            }

            System.out.println();

        }
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int h, w;

        while(true) {
            h = sc.nextInt();
            w = sc.nextInt();
            
            if (h == 0 && w == 0) {
                break;
            }

            StringBuilder sb1 = new StringBuilder();
            StringBuilder sb2 = new StringBuilder();

            for (int i = 0; i < w; i++) {
                if ((i % 2) == 0) {
                    sb1.append("#");
                    sb2.append(".");
                } else {
                    sb1.append(".");
                    sb2.append("#");
                }
            }
            

            for (int j = 0; j < h; j++) {
                if ((j % 2) == 0) {
                    System.out.println(sb1);
                } else {
                    System.out.println(sb2);
                }

            }

            System.out.println();

        }
    } main {
        Scanner sc = new Scanner(System.in);

        int h, w;

        while(true) {
            h = sc.nextInt();
            w = sc.nextInt();
            
            if (h == 0 && w == 0) {
                break;
            }

            StringBuilder sb1 = new StringBuilder();
            StringBuilder sb2 = new StringBuilder();

            for (int i = 0; i < w; i++) {
                if ((i % 2) == 0) {
                    sb1.append("#");
                    sb2.append(".");
                } else {
                    sb1.append(".");
                    sb2.append("#");
                }
            }
            

            for (int j = 0; j < h; j++) {
                if ((j % 2) == 0) {
                    System.out.println(sb1);
                } else {
                    System.out.println(sb2);
                }

            }

            System.out.println();

        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int h h w; w while(true) {
            h = sc.nextInt();
            w = sc.nextInt();
            
            if (h == 0 && w == 0) {
                break;
            }

            StringBuilder sb1 = new StringBuilder();
            StringBuilder sb2 = new StringBuilder();

            for (int i = 0; i < w; i++) {
                if ((i % 2) == 0) {
                    sb1.append("#");
                    sb2.append(".");
                } else {
                    sb1.append(".");
                    sb2.append("#");
                }
            }
            

            for (int j = 0; j < h; j++) {
                if ((j % 2) == 0) {
                    System.out.println(sb1);
                } else {
                    System.out.println(sb2);
                }

            }

            System.out.println();

        } true {
            h = sc.nextInt();
            w = sc.nextInt();
            
            if (h == 0 && w == 0) {
                break;
            }

            StringBuilder sb1 = new StringBuilder();
            StringBuilder sb2 = new StringBuilder();

            for (int i = 0; i < w; i++) {
                if ((i % 2) == 0) {
                    sb1.append("#");
                    sb2.append(".");
                } else {
                    sb1.append(".");
                    sb2.append("#");
                }
            }
            

            for (int j = 0; j < h; j++) {
                if ((j % 2) == 0) {
                    System.out.println(sb1);
                } else {
                    System.out.println(sb2);
                }

            }

            System.out.println();

        } h = sc.nextInt() h sc.nextInt() sc.nextInt sc w = sc.nextInt() w sc.nextInt() sc.nextInt sc if (h == 0 && w == 0) {
                break;
            } h == 0 && w == 0 h == 0 h 0 w == 0 w 0 {
                break;
            } break; StringBuilder sb1 = new StringBuilder(); sb1 new StringBuilder() StringBuilder sb2 = new StringBuilder(); sb2 new StringBuilder() for (int i = 0; i < w; i++) {
                if ((i % 2) == 0) {
                    sb1.append("#");
                    sb2.append(".");
                } else {
                    sb1.append(".");
                    sb2.append("#");
                }
            } int i = 0; int i = 0; i 0 i < w i w i++ i++ i {
                if ((i % 2) == 0) {
                    sb1.append("#");
                    sb2.append(".");
                } else {
                    sb1.append(".");
                    sb2.append("#");
                }
            } {
                if ((i % 2) == 0) {
                    sb1.append("#");
                    sb2.append(".");
                } else {
                    sb1.append(".");
                    sb2.append("#");
                }
            } if ((i % 2) == 0) {
                    sb1.append("#");
                    sb2.append(".");
                } else {
                    sb1.append(".");
                    sb2.append("#");
                } (i % 2) == 0 (i % 2) i 2 0 {
                    sb1.append("#");
                    sb2.append(".");
                } sb1.append("#") sb1.append sb1 "#" sb2.append(".") sb2.append sb2 "." {
                    sb1.append(".");
                    sb2.append("#");
                } sb1.append(".") sb1.append sb1 "." sb2.append("#") sb2.append sb2 "#" for (int j = 0; j < h; j++) {
                if ((j % 2) == 0) {
                    System.out.println(sb1);
                } else {
                    System.out.println(sb2);
                }

            } int j = 0; int j = 0; j 0 j < h j h j++ j++ j {
                if ((j % 2) == 0) {
                    System.out.println(sb1);
                } else {
                    System.out.println(sb2);
                }

            } {
                if ((j % 2) == 0) {
                    System.out.println(sb1);
                } else {
                    System.out.println(sb2);
                }

            } if ((j % 2) == 0) {
                    System.out.println(sb1);
                } else {
                    System.out.println(sb2);
                } (j % 2) == 0 (j % 2) j 2 0 {
                    System.out.println(sb1);
                } System.out.println(sb1) System.out.println System.out System System.out sb1 {
                    System.out.println(sb2);
                } System.out.println(sb2) System.out.println System.out System System.out sb2 System.out.println() System.out.println System.out System System.out String[] args args public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int h, w;

        while(true) {
            h = sc.nextInt();
            w = sc.nextInt();
            
            if (h == 0 && w == 0) {
                break;
            }

            StringBuilder sb1 = new StringBuilder();
            StringBuilder sb2 = new StringBuilder();

            for (int i = 0; i < w; i++) {
                if ((i % 2) == 0) {
                    sb1.append("#");
                    sb2.append(".");
                } else {
                    sb1.append(".");
                    sb2.append("#");
                }
            }
            

            for (int j = 0; j < h; j++) {
                if ((j % 2) == 0) {
                    System.out.println(sb1);
                } else {
                    System.out.println(sb2);
                }

            }

            System.out.println();

        }
    }
} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int h, w;

        while(true) {
            h = sc.nextInt();
            w = sc.nextInt();
            
            if (h == 0 && w == 0) {
                break;
            }

            StringBuilder sb1 = new StringBuilder();
            StringBuilder sb2 = new StringBuilder();

            for (int i = 0; i < w; i++) {
                if ((i % 2) == 0) {
                    sb1.append("#");
                    sb2.append(".");
                } else {
                    sb1.append(".");
                    sb2.append("#");
                }
            }
            

            for (int j = 0; j < h; j++) {
                if ((j % 2) == 0) {
                    System.out.println(sb1);
                } else {
                    System.out.println(sb2);
                }

            }

            System.out.println();

        }
    }
} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int h, w;

        while(true) {
            h = sc.nextInt();
            w = sc.nextInt();
            
            if (h == 0 && w == 0) {
                break;
            }

            StringBuilder sb1 = new StringBuilder();
            StringBuilder sb2 = new StringBuilder();

            for (int i = 0; i < w; i++) {
                if ((i % 2) == 0) {
                    sb1.append("#");
                    sb2.append(".");
                } else {
                    sb1.append(".");
                    sb2.append("#");
                }
            }
            

            for (int j = 0; j < h; j++) {
                if ((j % 2) == 0) {
                    System.out.println(sb1);
                } else {
                    System.out.println(sb2);
                }

            }

            System.out.println();

        }
    }
}