# Very Easy!!!

Easy

Execution time limit is 1 second

Runtime memory usage limit is 128 megabytes

You are given the value of n and a. Determine the answer for the following series:

## Input

Two positive integers n and a.

## Output

Print the value of sum. It is known that the result is no more than `10^18`

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## Examples

Input #1

Answer #1

Input #2

Answer #2

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