import java.util.*;
 
class Main{
    public static void main(String[] arg){
        Scanner sc = new Scanner(System.in);
        while(true){
            int h = sc.nextInt();   
            int w = sc.nextInt();
            if (h == 0 && w == 0)break;
            StringBuilder sb = new StringBuilder();
            for(int i = 0; i < h; i++){
                for(int j=0; j < w; j++){
                    if( (i%2 == 0 && j%2 == 0)||(i%2 == 1 && j%2 == 1)){
                        sb.append("#");
                    }
                    else{
                        sb.append(".");
                    }
                }
                sb.append("\n");
            }
            System.out.println(sb);
        }   
    }
} import java.util.*; util.* java class Main{
    public static void main(String[] arg){
        Scanner sc = new Scanner(System.in);
        while(true){
            int h = sc.nextInt();   
            int w = sc.nextInt();
            if (h == 0 && w == 0)break;
            StringBuilder sb = new StringBuilder();
            for(int i = 0; i < h; i++){
                for(int j=0; j < w; j++){
                    if( (i%2 == 0 && j%2 == 0)||(i%2 == 1 && j%2 == 1)){
                        sb.append("#");
                    }
                    else{
                        sb.append(".");
                    }
                }
                sb.append("\n");
            }
            System.out.println(sb);
        }   
    }
} Main public static void main(String[] arg){
        Scanner sc = new Scanner(System.in);
        while(true){
            int h = sc.nextInt();   
            int w = sc.nextInt();
            if (h == 0 && w == 0)break;
            StringBuilder sb = new StringBuilder();
            for(int i = 0; i < h; i++){
                for(int j=0; j < w; j++){
                    if( (i%2 == 0 && j%2 == 0)||(i%2 == 1 && j%2 == 1)){
                        sb.append("#");
                    }
                    else{
                        sb.append(".");
                    }
                }
                sb.append("\n");
            }
            System.out.println(sb);
        }   
    } main {
        Scanner sc = new Scanner(System.in);
        while(true){
            int h = sc.nextInt();   
            int w = sc.nextInt();
            if (h == 0 && w == 0)break;
            StringBuilder sb = new StringBuilder();
            for(int i = 0; i < h; i++){
                for(int j=0; j < w; j++){
                    if( (i%2 == 0 && j%2 == 0)||(i%2 == 1 && j%2 == 1)){
                        sb.append("#");
                    }
                    else{
                        sb.append(".");
                    }
                }
                sb.append("\n");
            }
            System.out.println(sb);
        }   
    } 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;
            StringBuilder sb = new StringBuilder();
            for(int i = 0; i < h; i++){
                for(int j=0; j < w; j++){
                    if( (i%2 == 0 && j%2 == 0)||(i%2 == 1 && j%2 == 1)){
                        sb.append("#");
                    }
                    else{
                        sb.append(".");
                    }
                }
                sb.append("\n");
            }
            System.out.println(sb);
        } true {
            int h = sc.nextInt();   
            int w = sc.nextInt();
            if (h == 0 && w == 0)break;
            StringBuilder sb = new StringBuilder();
            for(int i = 0; i < h; i++){
                for(int j=0; j < w; j++){
                    if( (i%2 == 0 && j%2 == 0)||(i%2 == 1 && j%2 == 1)){
                        sb.append("#");
                    }
                    else{
                        sb.append(".");
                    }
                }
                sb.append("\n");
            }
            System.out.println(sb);
        } 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; StringBuilder sb = new StringBuilder(); sb new StringBuilder() for(int i = 0; i < h; i++){
                for(int j=0; j < w; j++){
                    if( (i%2 == 0 && j%2 == 0)||(i%2 == 1 && j%2 == 1)){
                        sb.append("#");
                    }
                    else{
                        sb.append(".");
                    }
                }
                sb.append("\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 && j%2 == 0)||(i%2 == 1 && j%2 == 1)){
                        sb.append("#");
                    }
                    else{
                        sb.append(".");
                    }
                }
                sb.append("\n");
            } {
                for(int j=0; j < w; j++){
                    if( (i%2 == 0 && j%2 == 0)||(i%2 == 1 && j%2 == 1)){
                        sb.append("#");
                    }
                    else{
                        sb.append(".");
                    }
                }
                sb.append("\n");
            } for(int j=0; j < w; j++){
                    if( (i%2 == 0 && j%2 == 0)||(i%2 == 1 && j%2 == 1)){
                        sb.append("#");
                    }
                    else{
                        sb.append(".");
                    }
                } int j=0; int j=0; j 0 j < w j w j++ j++ j {
                    if( (i%2 == 0 && j%2 == 0)||(i%2 == 1 && j%2 == 1)){
                        sb.append("#");
                    }
                    else{
                        sb.append(".");
                    }
                } {
                    if( (i%2 == 0 && j%2 == 0)||(i%2 == 1 && j%2 == 1)){
                        sb.append("#");
                    }
                    else{
                        sb.append(".");
                    }
                } if( (i%2 == 0 && j%2 == 0)||(i%2 == 1 && j%2 == 1)){
                        sb.append("#");
                    }
                    else{
                        sb.append(".");
                    } (i%2 == 0 && j%2 == 0)||(i%2 == 1 && j%2 == 1) (i%2 == 0 && j%2 == 0) i%2 == 0 i%2 i 2 0 j%2 == 0 j%2 j 2 0 (i%2 == 1 && j%2 == 1) i%2 == 1 i%2 i 2 1 j%2 == 1 j%2 j 2 1 {
                        sb.append("#");
                    } sb.append("#") sb.append sb "#" {
                        sb.append(".");
                    } sb.append(".") sb.append sb "." sb.append("\n") sb.append sb "\n" System.out.println(sb) System.out.println System.out System System.out sb String[] arg arg
import java.util.*;
 
class Main{
    public static void main(String[] arg){
        Scanner sc = new Scanner(System.in);
        while(true){
            int h = sc.nextInt();   
            int w = sc.nextInt();
            if (h == 0 && w == 0)break;
            StringBuilder sb = new StringBuilder();
            for(int i = 0; i < h; i++){
                for(int j=0; j < w; j++){
                    if( (i%2 == 0 && j%2 == 0)||(i%2 == 1 && j%2 == 1)){
                        sb.append("#");
                    }
                    else{
                        sb.append(".");
                    }
                }
                sb.append("\n");
            }
            System.out.println(sb);
        }   
    }
}