E. Accurate Medals
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

At each ICPC contest, there are three types of medals Gold, Silver, and Bronze.

Each winning team consists of exactly 3 members, and each member receives one medal of the same type as their team.

After being denied his medals twice because the organizers undercounted the required number, Qatada decided that this will never happen again. For every contest he organizes, he wants to buy the exact number of medals needed for all winning teams.

He goes to a medals store to buy medals for $$$n$$$ winning teams. The seller asks him:

"How many medals do you need?"

Qatada suddenly remembers that he is not very good at calculations, so he calls the best coach, Ayoub.

Ayoub hears the problem, but he is currently busy at work, so he forwards the question to you.

Can you help them compute the exact number of medals required?

Input

The first and only line of input consists of a single integer $$$n$$$ ($$$1 \le n \le 10^{8}$$$) — the number of winning teams.

Output

Print a single integer — the total number of medals required.

Examples
Input
9
Output
27
Input
1
Output
3