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/2;i++){
for(int j=0;j<W/2;j++){
    System.out.printf("#.");
    
  }
  if(W%2 == 1){
    System.out.printf("#");   
    }
    System.out.printf("\n");
for(int j=0;j<W/2;j++){
    System.out.printf(".#");
}
    if(W%2 == 1){
        System.out.printf(".");   
        }
   
    System.out.printf("\n");
    }
    if(H%2 == 1){
        for(int j=0;j<W/2;j++){
        
 System.out.printf("#.");
        }
 if(W%2 == 1){
    System.out.printf("#");   
    }
        

  System.out.printf("\n\n");
    }

    }
            
    }
    }

