# -*- coding: utf-8 -*-
"""
No.192 合成数
https://yukicoder.me/problems/no/192

"""
import sys
from sys import stdin
input = stdin.readline


def main(args):
    N = int(input())
    if N % 2 == 0:
        print(N)
    else:
        print(N+1)


if __name__ == '__main__':
    main(sys.argv[1:])