Guilherme and His Kites
By Gustavo Ribeiro, IFPB - Campina Grande 
Brazil
By Gustavo Ribeiro, IFPB - Campina Grande Brazil
Guilherme loves kites, kites of different colors, forms and sizes. He realized that in order to kites become stable, and thus fly higher, they must have a taut string connecting all pairs of non-neighboors tips.
Despite being a very creative and clever child, Guilherme doesn’t know how to determine the number of strings necessary to make a kite of n sides stable. Could you help him?
The single line of the input contains an integer 3 ≤ n ≤ 105, the number of sides of the kite.
Print a single number, the number of strings that Guilherme needs to make a kite of n sides stable.
| Input Samples | Output Samples |
|
4 |
2 |
|
10 |
35 |
|
11 |
44 |