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