import time
def make_dice(sides = 6, seed = None):
    """A new 'sides'-sided die that yields numbers between 1 and
    'sides' when called.  'seed' controls the sequence of values.
    If it is defaulted, the system chooses a non-deterministic value."""

    if seed == None:
         seed = int(time.time() * 100000)
    a, c, m = 25214903917, 11, 2**48  # From Java

    def die():
        nonlocal seed
        seed = (a*seed + c) % m
        return seed % sides + 1
    return die

def frequencies(L):
    """A dictionary giving, for each w in L, the number of times w 
    appears in L.
    >>> frequencies(['the', 'name', 'of', 'the', 'name', 'of', 'the',
    ...              'song'])
    {'of': 2, 'the': 3, 'name': 2, 'song': 1}
    """
    return { L[i-1]: L[i] for i in range(1, len(L)) }

# Or, the long way:

def frequencies2(L):
    """A dictionary giving, for each w in L, the number of times w 
    appears in L.
    >>> frequencies(['the', 'name', 'of', 'the', 'name', 'of', 'the',
    ...              'song'])
    {'of': 2, 'the': 3, 'name': 2, 'song': 1}
    """
    result = {}
    for i in range(1, len(L)):
        result[L[i-1]] = L[i]
    return result

def is_duplicate(L):
    """True iff L contains a duplicated item."""
    items = {}
    for x in L:
        if x in items: return True
        items[x] = True   # Or any value
    return False

def common_keys(D0, D1):
    """Return dictionary containing the keys common to D0 and D1."""
    result = {}
    for x in D0:
         if x in D1: result[x] = True
    return result


def make_counter():
    """Returns a function that returns the next higher integer
    each time it is called, starting with 0.
    >>> c = make_counter()
    >>> c()
    0
    >>> c()
    1
    >>> c()
    2
    """
    count = 0
    def counter():
        nonlocal count
        count += 1
        return count - 1
    return counter

def make_account(balance):
  """A new bank account with initial balance `balance`. 
  If acc is an account returned by make_account, then
  acc('balance') returns the current balance.
  acc('deposit', d) deposits d cents into the account
  acc('withdraw', w) withdraws w cents from the account, if
     possible.
  'deposit' and 'withdraw' return acc itself.
  >>> a = make_account(100)
  >>> a('balance')
  100
  >>> a('withdraw', 10)
  >>> a('balance')
  90
"""

  def acc(op, *opnds):
      nonlocal balance
      if op == 'balance' and len(opnds) == 0:
           return balance
      elif op == 'deposit' and len(opnds) == 1 and opnds[0] > 0:
           balance += opnds[0]
      elif op == 'withdraw' and len(opnds) == 1 \
           and 0 <= opnds[0] <= balance:
           balance -= opnds[0]
      else: raise ValueError()
  return acc