def check(credit_card_number):

    credit_card_number = str(credit_card_number)
    count1 = 0
    count2 = 0
    z = ""

    for n in range(len(credit_card_number)-1, -1, -2):
        x = int(credit_card_number[n])
        count1 += x

    for n in range(len(credit_card_number)-2, -1, -2):
        y = int(credit_card_number[n])
        y = y*2
        z += str(y)

    for n in range(len(z)):
        a = int(z[n])
        count2 += a

    total = count1 + count2

    if total % 10 == 0:
        return True
    else:
        return False