Pentagonal numbers

3000ms

262144K

Description:

Pentagonal numbers are figurate numbers which can be calculated using the formula p_n = (3n² - n) / 2 (always integer). You are given n; calculate n-th pentagonal number.

Input:

The only line of input contains an integer n (1 ≤ n ≤ 100).

Output:

Output the n-th pentagonal number.

Sample Input:

Sample Output:

Sample Input:

Sample Output:

Informação

Provedor Codeforces

Código CF162A