PROGRAMMING:Jiliang Jiying doesn't work
Jiliang Jiying is an ordinary office worker. He knows from his boss that he will have N working days next. Because continuous work will make employees less efficient, the company feels that Jiliang Jiying can ask for leave on the days of mutual quality with N. Jiliang Jiying wants to know how many days he has. Can you tell him as soon as possible（ After all, your doorknob has been touched by the killer queen.
###Input format:
Enter the number of days for Jiliang Jiying to work, N, n < = 2e8
##Output format:
Output the number of days that Jiliang Jiying can ask for leave
###Input example:
Here is a set of inputs. For example:
```in
fifteen
```
###Output example:
The corresponding output is given here. For example:
```out
eight
```
answer：If there is no answer, please comment
###Input format:
Enter the number of days for Jiliang Jiying to work, N, n < = 2e8
##Output format:
Output the number of days that Jiliang Jiying can ask for leave
###Input example:
Here is a set of inputs. For example:
```in
fifteen
```
###Output example:
The corresponding output is given here. For example:
```out
eight
```
answer：If there is no answer, please comment