Recursive Bunny Ears

Background

Congcong loves small animals, especially cute bunnies. He noticed that different bunnies have different numbers of ears.

Problem Description

We have bunnies standing in a line, numbered $1, 2, \dots$. The odd bunnies ($1, 3, \dots$) have the normal $2$ ears. The even bunnies ($2, 4, \dots$) we'll say have $3$ ears, because they each have a raised foot. Recursively return the number of "ears" in the bunny line $1, 2, \dots, n$ (without loops or multiplication).

Input Format

Input is given from Standard Input in the following format.

An integer $n$, representing the length of the bunny line.

Output Format

Output is printed to Standard Output in the following format.

An integer, representing the total number of ears for the first $n$ bunnies.

Sample

0

0

1

2

2

5

Sample Explanation

For $n=0$, there are no bunnies, so the total number of ears is $0$. For $n=1$, there is only bunny $1$, which is odd-numbered and has $2$ ears. Total is $2$. For $n=2$, there are bunny $1$ and bunny $2$. Bunny $1$ is odd-numbered and has $2$ ears. Bunny $2$ is even-numbered and has $3$ ears. Total is $2 + 3 = 5$.

Constraints

Time limit: $1$ second, Memory limit: $1024$ KiB for each test case.