from itertools import count

def numbers():
  for n in count():
    yield str(n)

def terms():
  def parens():
    for exp in expressions():
      yield "(" + exp + ")"
  return alternate(numbers, parens)

def mul():
  def mul2():
    for a, b in combine(mul, terms):
      yield a + "*" + b
  return alternate(terms, mul2)

def add():
  def add2():
    for a, b in combine(add, mul):
      yield a + "+" + b
  return alternate(mul, add2)

expressions = add

def alternate(s, t):
  x = s()
  y = t()
  while True:
    yield x.next()
    yield y.next()

def combine(s, t):
  for n in count(1):
    comb = [x for x in partial_combination(s, t, n)]
    #print "comb", n, comb
    if len(comb) == 0:
      return
    else:
      for p in comb:
        yield p

def take_first(s, n):
  x = s()
  for i in range(0, n):
    yield x.next()

def partial_combination(s, t, n):
  vals = [val for val in take_first(s, n)]
  for i in range(len(vals), n):
    vals.append(None)
  vals.reverse()
  ygen = t()
  for x in vals:
    try:
      y = ygen.next()
      if x is not None:
        yield (x, y)
    except:
      if x is None: return

for e in expressions():
  print e