Problem:
Score : 100 points

Problem Statement

You are given a positive integer N.
Find the minimum positive integer divisible by both 2 and N.

Constraints

1 \leq N \leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N

Output

Print the minimum positive integer divisible by both 2 and N.

Sample Input 1

3

Sample Output 1

6

6 is divisible by both 2 and 3.
Also, there is no positive integer less than 6 that is divisible by both 2 and 3.
Thus, the answer is 6.

Sample Input 2

10

Sample Output 2

10

Sample Input 3

999999999

Sample Output 3

1999999998

Solution in Rust (1.15.1) (judge verdict: Accepted)


fn main(){
    let mut n:i32 = getline().trim().parse().unwrap();
    if (n % 2 != 0) {
        n *= 2;
    }
    println!("{}", n);
}

fn getline() -> String{
    let mut r = String::new();
    std::io::stdin().read_line(&mut r).ok();
    return r;
}