import java.util.*;

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

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        
        int i,j;
        
        while(true){
        int n = sc.nextInt();
        int m = sc.nextInt();
        if(n==0 && m==0){
            break;
        }
        for(i=0;i<n;i++){
            for(j=0;j<m;j++){
                if(((j+i)%2)==0){
                    System.out.printf("#");
                }else{
                System.out.printf(".");
                }
                
            }
            System.out.println();
        }
        System.out.println();
    }
    }
}
