PROGRAMMING:4.21 - display a square pattern with an integer as the side length
Write a program to show the square with the length of the input integer as the side.
-----From exercise 4-21
```
Make a square
A square has several layers: 3
***
***
***
```
###Input example:
```in
three
```
###Output example:
```out
Make a square
A square has several layers:***
***
***
```
answer：If there is no answer, please comment
-----From exercise 4-21
```
Make a square
A square has several layers: 3
***
***
***
```
###Input example:
```in
three
```
###Output example:
```out
Make a square
A square has several layers:***
***
***
```
answer：If there is no answer, please comment