Grandpa's Clear Path

In the quiet countryside, an elderly grandpa walks without wanting to wander in circles, because doing so makes him drowsy. One day, he meets Xia A, who, carrying a map and upholding the spirit of helpfulness, wonders whether the road conditions will keep him alert. Meanwhile, Xia A has some math homework for you.

You are given two integers, R and N. If R is even, compute the sum of the first N even numbers; if R is odd, compute the sum of the first N odd numbers.

The formulas are as follows:

• When R is even: \(S = N \times (N+1)\)
• When R is odd: \(S = N^2\)

inputFormat

The input consists of two space-separated integers: R and N.

outputFormat

Output a single integer according to the conditions provided.

sample

2 3

12