Student A and student B are giving each other test answers during a test.  
They don't want to be caught so they are sending each other coded messages.
Student A is sending student B the message: `Answer to Number 5 Part b`.  
He starts of with a square grid (in this example the grid = 5x5).  
He writes the message down (with spaces):
```
Answe
r to 
Numbe
r 5 P
art b
```
He then starts writing the message down one column at a time (from the top to the bottom).  
The new message is now: `ArNran u rstm5twob  e ePb`
You are the teacher of this class.  
Your job is to decipher this message and bust the students.
# Task
Write a function `decipher_message`.  
This function will take one parameter (`message`).  
This function will return the original message.  
*** Note: The length of the string is always going to be a prefect square ***
Hint: You should probably decipher the example message first before you start coding
Have fun !!!
import math
def decipher_message(m):
    l = int(math.sqrt(len(m)))  
    return ''.join(''.join(m[i+l*j] for j in range(l)) for i in range(l))
import math
def decipher_message(m):
    l = int(math.sqrt(len(m)))  
    return ''.join(''.join(m[i+l*j] for j in range(l)) for i in range(l))