# CF979A Pizza, Pizza, Pizza!!!

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## 题意翻译

Shiro过生日啦！她请了$n$个好朋友来庆祝自己的生日。

为了庆祝，她拿出了一份非常大的披萨。她想把这份披萨切成$n+1$份(她自己也要吃)。这$n+1$份要求大小和形状都一样。那么Shiro最少要切多少刀？

ps:切披萨时，只能切直线，不能把披萨摞起来切

$0\le n \le 10^{18}$

## 题目描述

Katie, Kuro and Shiro are best friends. They have known each other since kindergarten. That's why they often share everything with each other and work together on some very hard problems.

Today is Shiro's birthday. She really loves pizza so she wants to invite her friends to the pizza restaurant near her house to celebrate her birthday, including her best friends Katie and Kuro.

She has ordered a very big round pizza, in order to serve her many friends. Exactly $n$ of Shiro's friends are here. That's why she has to divide the pizza into $n + 1$ slices (Shiro also needs to eat). She wants the slices to be exactly the same size and shape. If not, some of her friends will get mad and go home early, and the party will be over.

Shiro is now hungry. She wants to cut the pizza with minimum of straight cuts. A cut is a straight segment, it might have ends inside or outside the pizza. But she is too lazy to pick up the calculator.

As usual, she will ask Katie and Kuro for help. But they haven't come yet. Could you help Shiro with this problem?

## 输入输出格式

输入格式：

A single line contains one non-negative integer $n$ ( $0 \le n \leq 10^{18}$ ) — the number of Shiro's friends. The circular pizza has to be sliced into $n + 1$ pieces.

输出格式：

A single integer — the number of straight cuts Shiro needs.

## 输入输出样例

输入样例#1： 复制
3

输出样例#1： 复制
2
输入样例#2： 复制
4

输出样例#2： 复制
5

## 说明

To cut the round pizza into quarters one has to make two cuts through the center with angle $90^{\circ}$ between them.

To cut the round pizza into five equal parts one has to make five cuts.

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