Problem C: Destroy all balls ## Problem C: Destroy all balls

Time Limit: 1 Sec Memory Limit: 128 MB

Submit: 81 Solved: 38

[Submit][Status][Web Board]## Description

There
are n boxes in a line. At first, each box contains only one ball. There is a
special machine. For each operation, the machine can attack a box. Once a ball
is attacked, it will jump into the adjacent boxes. When a ball is attacked by twice,
it will be destroyed. Please find the minimum number of operations that can destroy
all balls.

## Input

Only
one line with an integer n. (2 <= n <= 10^{5})

## Output

One
line contains the minimum number of operations that can destroy all balls.

## Sample Input

2

## Sample Output

3

## HINT

[Submit][Status]