import java.util.Scanner;
public class Main{
    public static void main (String [] args){
        Scanner sc =new Scanner(System.in);
        int i=1;
        while(true){
        
            int H =sc.nextInt();
            int W =sc.nextInt();

        if(H==0 && W==0)break;
        for(int b=0;b<H;b++){
            int n=b;
           for(int a=0;a<W;a++){
            
            if(n%2==0)System.out.printf("#");
            else     System.out.printf(".");
            n++;
        }
        System.out.println();
        }
        System.out.println();
    }       
        sc.close();
   }
 
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main (String [] args){
        Scanner sc =new Scanner(System.in);
        int i=1;
        while(true){
        
            int H =sc.nextInt();
            int W =sc.nextInt();

        if(H==0 && W==0)break;
        for(int b=0;b<H;b++){
            int n=b;
           for(int a=0;a<W;a++){
            
            if(n%2==0)System.out.printf("#");
            else     System.out.printf(".");
            n++;
        }
        System.out.println();
        }
        System.out.println();
    }       
        sc.close();
   }
 
} Main public static void main (String [] args){
        Scanner sc =new Scanner(System.in);
        int i=1;
        while(true){
        
            int H =sc.nextInt();
            int W =sc.nextInt();

        if(H==0 && W==0)break;
        for(int b=0;b<H;b++){
            int n=b;
           for(int a=0;a<W;a++){
            
            if(n%2==0)System.out.printf("#");
            else     System.out.printf(".");
            n++;
        }
        System.out.println();
        }
        System.out.println();
    }       
        sc.close();
   } main {
        Scanner sc =new Scanner(System.in);
        int i=1;
        while(true){
        
            int H =sc.nextInt();
            int W =sc.nextInt();

        if(H==0 && W==0)break;
        for(int b=0;b<H;b++){
            int n=b;
           for(int a=0;a<W;a++){
            
            if(n%2==0)System.out.printf("#");
            else     System.out.printf(".");
            n++;
        }
        System.out.println();
        }
        System.out.println();
    }       
        sc.close();
   } Scanner sc =new Scanner(System.in); sc new Scanner(System.in) int i=1; i 1 while(true){
        
            int H =sc.nextInt();
            int W =sc.nextInt();

        if(H==0 && W==0)break;
        for(int b=0;b<H;b++){
            int n=b;
           for(int a=0;a<W;a++){
            
            if(n%2==0)System.out.printf("#");
            else     System.out.printf(".");
            n++;
        }
        System.out.println();
        }
        System.out.println();
    } true {
        
            int H =sc.nextInt();
            int W =sc.nextInt();

        if(H==0 && W==0)break;
        for(int b=0;b<H;b++){
            int n=b;
           for(int a=0;a<W;a++){
            
            if(n%2==0)System.out.printf("#");
            else     System.out.printf(".");
            n++;
        }
        System.out.println();
        }
        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)break; H==0 && W==0 H==0 H 0 W==0 W 0 break; for(int b=0;b<H;b++){
            int n=b;
           for(int a=0;a<W;a++){
            
            if(n%2==0)System.out.printf("#");
            else     System.out.printf(".");
            n++;
        }
        System.out.println();
        } int b=0; int b=0; b 0 b<H b H b++ b++ b {
            int n=b;
           for(int a=0;a<W;a++){
            
            if(n%2==0)System.out.printf("#");
            else     System.out.printf(".");
            n++;
        }
        System.out.println();
        } {
            int n=b;
           for(int a=0;a<W;a++){
            
            if(n%2==0)System.out.printf("#");
            else     System.out.printf(".");
            n++;
        }
        System.out.println();
        } int n=b; n b for(int a=0;a<W;a++){
            
            if(n%2==0)System.out.printf("#");
            else     System.out.printf(".");
            n++;
        } int a=0; int a=0; a 0 a<W a W a++ a++ a {
            
            if(n%2==0)System.out.printf("#");
            else     System.out.printf(".");
            n++;
        } {
            
            if(n%2==0)System.out.printf("#");
            else     System.out.printf(".");
            n++;
        } if(n%2==0)System.out.printf("#");
            else     System.out.printf("."); n%2==0 n%2 n 2 0 System.out.printf("#") System.out.printf System.out System System.out "#" System.out.printf(".") System.out.printf System.out System System.out "." n++ n System.out.println() System.out.println System.out System System.out System.out.println() System.out.println System.out System System.out sc.close() sc.close sc String [] args args public class Main{
    public static void main (String [] args){
        Scanner sc =new Scanner(System.in);
        int i=1;
        while(true){
        
            int H =sc.nextInt();
            int W =sc.nextInt();

        if(H==0 && W==0)break;
        for(int b=0;b<H;b++){
            int n=b;
           for(int a=0;a<W;a++){
            
            if(n%2==0)System.out.printf("#");
            else     System.out.printf(".");
            n++;
        }
        System.out.println();
        }
        System.out.println();
    }       
        sc.close();
   }
 
} public class Main{
    public static void main (String [] args){
        Scanner sc =new Scanner(System.in);
        int i=1;
        while(true){
        
            int H =sc.nextInt();
            int W =sc.nextInt();

        if(H==0 && W==0)break;
        for(int b=0;b<H;b++){
            int n=b;
           for(int a=0;a<W;a++){
            
            if(n%2==0)System.out.printf("#");
            else     System.out.printf(".");
            n++;
        }
        System.out.println();
        }
        System.out.println();
    }       
        sc.close();
   }
 
} Main
import java.util.Scanner;
public class Main{
    public static void main (String [] args){
        Scanner sc =new Scanner(System.in);
        int i=1;
        while(true){
        
            int H =sc.nextInt();
            int W =sc.nextInt();

        if(H==0 && W==0)break;
        for(int b=0;b<H;b++){
            int n=b;
           for(int a=0;a<W;a++){
            
            if(n%2==0)System.out.printf("#");
            else     System.out.printf(".");
            n++;
        }
        System.out.println();
        }
        System.out.println();
    }       
        sc.close();
   }
 
}
