A. Pentagonal numberstime limit per test3 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard outputPentagonal numbers are figurate numbers which can be calculated using the formula pn = (3n2 - n) / 2 (always integer). You are given n; calculate n-th pentagonal number.InputThe only line of input contains an integer n (1 ≤ n ≤ 100).OutputOutput the n-th pentagonal number.ExamplesInput2Output5Input5Output35
Input2
Output5
['*special problem', 'implementation', '*1100']