P403761 - GYM101262 A Vera and Outfits - SSOJ - 省实信息奥赛评测系统

Memory Limit：256 MB Time Limit：2 S

Judge Style：Text Compare Creator：

Submit：0 Solved：0

A. Vera and Outfitstime limit per test2 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard output

Vera owns N tops and N pants. The i-th top and i-th pants have colour i, for 1 ≤ i ≤ N, where all N colors are different from each other.

An outfit consists of one top and one pants. Vera likes outfits where the top and pants are not the same colour.

How many different outfits does she like?

Constraints:

1 ≤ N ≤ 2017

N is integer

Input

The input will be in the format:

Output

Output one line with the number of different outfits Vera likes.

ExamplesInput

Output

Input

Output

Input

Output

403761: GYM101262 A Vera and Outfits