COCI 2009/2010, Contest #1

Task DOMINO

Dominoes are gaming pieces used in numerous tile games. Each doimno piece contains two marks. Each mark consists of a number of spots (possibly zero). The number of spots depends on the set size. Each mark in a size N domino set can contain between 0 and N spots, inclusive. Two tiles are considered identical if their marks have the same number of spots, irregardles of reading order. For example tile with 2 and 8 spot marks is identical to the tile having 8 and 2 spot marks. A proper domino set contains no duplicate tiles. A complete set of size N contains all posible tiles with N or less spots and no duplicate tiles. For example, the complete set of size 2 contains 6 tiles:

Write a program that will determine the total number of spots on all tiles of a complete size N set.

Input

The first and only line of input contains a single integer, N (1 ≤ N ≤ 1000), the size of the complete set.

Output

The first and only line of output should contain a single integer, total number of spots in a complete size N set.

Sample Tests

2

12

3

30

15

2040

Second sample description:

Size 3 set contains tiles: [0|0], [0|1], [0|2], [0|3], [1|1], [1|2], [1|3], [2|2], [2|3] and [3|3].

All Submissions
Best Solutions

Point Value: 5
Time Limit: 1.00s
Memory Limit: 32M
Added: Jul 02, 2013

Languages Allowed:
C++03, PAS, C, HASK, ASM, RUBY, PYTH2, JAVA, PHP, SCM, CAML, PERL, C#, C++11, PYTH3

Comments (Search)

"irregardles of reading order"
two mistakes, first "irregardles",should be regardless
and it has the letter "s" twice 

Irregardless is considered nonstandard but irregardless is a word and it means regardless.
[url]http://www.dictionary.com/browse/irregardless[/url]

https://en.wikipedia.org/wiki/Irregardless

irregardless of the problem's grammar, you should be able to solve it

I solved it already, chill

lol you don't know how to post clickable url's