题目描述

A fractal is an object or quantity that displays self-similarity, in a somewhat technical sense, on all scales. The object need not exhibit exactly the same structure at all scales, but the same "type" of structures must appear on all scales.

A box fractal is defined as below :

• A box fractal of degree $1$ is simply X
• A box fractal of degree $2$ is

X X
 X
X X

• If using $B(n - 1)$ to represent the box fractal of degree $n - 1$, then a box fractal of degree $n$ is defined recursively as following

B(n - 1) B(n - 1)
     B(n - 1)
B(n - 1) B(n - 1)

Your task is to draw a box fractal of degree $n$.

输入格式

The input consists of several test cases. Each line of the input contains a positive integer $n$ which is no greater than $7$. The last line of input is a negative integer $-1$ indicating the end of input.

输出格式

For each test case, output the box fractal using the 'X' notation. Please notice that 'X' is an uppercase letter. Print a line with only a single dash after each test case.

1
2
3 
4 
-1

X
-
X X
 X 
X X
-
X X   X X
 X     X 
X X   X X
   X X   
    X    
   X X   
X X   X X
 X     X 
X X   X X
-
X X   X X         X X   X X
 X     X           X     X 
X X   X X         X X   X X
   X X               X X   
    X                 X    
   X X               X X   
X X   X X         X X   X X
 X     X           X     X 
X X   X X         X X   X X
         X X   X X         
          X     X          
         X X   X X         
            X X            
             X             
            X X            
         X X   X X         
          X     X          
         X X   X X         
X X   X X         X X   X X
 X     X           X     X 
X X   X X         X X   X X
   X X               X X   
    X                 X    
   X X               X X   
X X   X X         X X   X X
 X     X           X     X 
X X   X X         X X   X X
-