def mcd(a, b):
    if (a == 0) or (b == 0):
        res = 0
    elif (a==b):
        res = a
    elif (a>b):
        res = mcd(a-b, b)
    else:
        res = mcd(b-a, a)
    return res


print(mcd(10,5))
print(mcd(0,2))