Problem A: Joana and the Odd Numbers
------------------------------------

Joana loves playing with odd numbers. In the other day, she started
writing, in each line, an odd number of odd numbers. It looked as
follows: 

 1
 3  5  7
 9 11 13 15 17
19 21 23 25 27 29 31
...

On a certain line Joana wrote 55 odd numbers. Can you discover the sum
of the last three numbers written in that line? Can you do this more
generally for any given quantity of odd numbers?  Efficiently?

In this problem, you will be given the number N of odd numbers in a
certain line. Your task is to determine the sum of the last three
numbers of that line. 

Input
-----

The input is a sequence of lines, one odd number N (1 < N < 2000) per line.
There will be at most 1000 lines (test cases).

Output
------

For each input line write the sum of the last three odd numbers written
by Joana in that line with N numbers. This sum is guaranteed to be less
than 2^31. 

Sample Input
------------
3
5
7

Output for Sample Input
-----------------------
15
45
87