import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();
            if(H == 0 && W == 0){
                break;
            }
            for(int i=0;i<H;i++){
                for(int j=0;j<W;j++){
                    if(i%2 == 0){
                        if(j%2 == 0){
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 == 0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                    }
                }
            }
            System.out.print("\n");
        }
        System.out.print("\n");
    }
}
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();
            if(H == 0 && W == 0){
                break;
            }
            for(int i=0;i<H;i++){
                for(int j=0;j<W;j++){
                    if(i%2 == 0){
                        if(j%2 == 0){
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 == 0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                    }
                }
            }
            System.out.print("\n");
        }
        System.out.print("\n");
    }
}
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();
            if(H == 0 && W == 0){
                break;
            }
            for(int i=0;i<H;i++){
                for(int j=0;j<W;j++){
                    if(i%2 == 0){
                        if(j%2 == 0){
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 == 0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                    }
                }
            }
            System.out.print("\n");
        }
        System.out.print("\n");
    }
} main {
        Scanner sc = new Scanner(System.in);
        while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();
            if(H == 0 && W == 0){
                break;
            }
            for(int i=0;i<H;i++){
                for(int j=0;j<W;j++){
                    if(i%2 == 0){
                        if(j%2 == 0){
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 == 0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                    }
                }
            }
            System.out.print("\n");
        }
        System.out.print("\n");
    }
} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();
            if(H == 0 && W == 0){
                break;
            }
            for(int i=0;i<H;i++){
                for(int j=0;j<W;j++){
                    if(i%2 == 0){
                        if(j%2 == 0){
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 == 0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                    }
                }
            }
            System.out.print("\n");
        }
        System.out.print("\n");
    } true {
            int H = sc.nextInt();
            int W = sc.nextInt();
            if(H == 0 && W == 0){
                break;
            }
            for(int i=0;i<H;i++){
                for(int j=0;j<W;j++){
                    if(i%2 == 0){
                        if(j%2 == 0){
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 == 0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                    }
                }
            }
            System.out.print("\n");
        }
        System.out.print("\n");
    } 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){
                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%2 == 0){
                        if(j%2 == 0){
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 == 0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                    }
                }
            }
            System.out.print("\n");
        } int i=0; int i=0; i 0 i<H i H i++ i++ i {
                for(int j=0;j<W;j++){
                    if(i%2 == 0){
                        if(j%2 == 0){
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 == 0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                    }
                }
            }
            System.out.print("\n");
        } {
                for(int j=0;j<W;j++){
                    if(i%2 == 0){
                        if(j%2 == 0){
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 == 0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                    }
                }
            }
            System.out.print("\n");
        } for(int j=0;j<W;j++){
                    if(i%2 == 0){
                        if(j%2 == 0){
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        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(i%2 == 0){
                        if(j%2 == 0){
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 == 0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                    }
                }
            } {
                    if(i%2 == 0){
                        if(j%2 == 0){
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 == 0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                    }
                }
            } if(i%2 == 0){
                        if(j%2 == 0){
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 == 0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                    }
                } i%2 == 0 i%2 i 2 0 {
                        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 "." {
                        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 "#" System.out.print("\n") System.out.print System.out System System.out "\n" System.out.print("\n") System.out.print System.out System System.out "\n" String[] args args public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();
            if(H == 0 && W == 0){
                break;
            }
            for(int i=0;i<H;i++){
                for(int j=0;j<W;j++){
                    if(i%2 == 0){
                        if(j%2 == 0){
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 == 0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                    }
                }
            }
            System.out.print("\n");
        }
        System.out.print("\n");
    }
}
} public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();
            if(H == 0 && W == 0){
                break;
            }
            for(int i=0;i<H;i++){
                for(int j=0;j<W;j++){
                    if(i%2 == 0){
                        if(j%2 == 0){
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 == 0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                    }
                }
            }
            System.out.print("\n");
        }
        System.out.print("\n");
    }
}
} Main
import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(true){
            int H = sc.nextInt();
            int W = sc.nextInt();
            if(H == 0 && W == 0){
                break;
            }
            for(int i=0;i<H;i++){
                for(int j=0;j<W;j++){
                    if(i%2 == 0){
                        if(j%2 == 0){
                            System.out.print("#");
                        }else{
                            System.out.print(".");
                        }
                    }else{
                        if(j%2 == 0){
                            System.out.print(".");
                        }else{
                            System.out.print("#");
                    }
                }
            }
            System.out.print("\n");
        }
        System.out.print("\n");
    }
}
}
