Package for this problem was not updated by the problem writer or Codeforces administration after we’ve upgraded the judging servers. To adjust the time limit constraint, solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then value 800 ms will be displayed and used to determine the verdict.

The following languages are additionally available for the problems from the contest

April Fools Day Contest:

- Secret_171

Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ACM-ICPC mode for virtual contests.
If you've seen these problems, a virtual contest is not for you - solve these problems in the archive.
If you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.
Never use someone else's code, read the tutorials or communicate with other person during a virtual contest.

No tag edit access

B. Star

time limit per test

2 secondsmemory limit per test

256 megabytesinput

standard inputoutput

standard outputInput

The input contains a single integer *a* (1 ≤ *a* ≤ 18257).

Output

Print a single integer *output* (1 ≤ *output* ≤ 2·10^{9}).

Examples

Input

2

Output

13

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