import fractions



def main():

    n = int(eval(input()))

    if n%2 == 0:

        print(n)

    else:

        print((2*n))





if __name__ == '__main__':

    main()

def main():

    n = int(eval(input()))

    if n%2 == 0:

        print(n)

    else:

        print((2*n))





if __name__ == '__main__':

    main()
import fractions


def main():
    n = int(eval(input()))
    if n % 2 == 0:
        print(n)
    else:
        print((2 * n))


if __name__ == "__main__":
    main()

def main():
    n = int(eval(input()))
    if n % 2 == 0:
        print(n)
    else:
        print((2 * n))


if __name__ == "__main__":
    main()

-import fractions - -