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 Go (1.14.1) (judge verdict: Accepted)

package main

import (
	"fmt"
)

func max(a, b int64) int64 {
	if a > b {
		return a
	}
	return b
}
func min(a, b int64) int64 {
	if a < b {
		return a
	}
	return b
}
func main() {
	var n int64
	fmt.Scan(&n)

	if n%2 == 0 {
		fmt.Println(n)
	} else {
		fmt.Println(2 * n)
	}
}