[백준] 4949

# 4949 균형잡힌 세상

while True :
  s = input()

  if(s == '.') :
    break
  check = []
  isBalanced = True
  for c in s :
    if c in ['(','['] :
      check.append(c)
    elif c in [')',']'] :
      if check :
        recentBracket = check.pop()
        if not ( (c is ')' and recentBracket is '(') or (c is ']' and recentBracket is '[')) :
          isBalanced = False
          break
      else : # check 배열이 비어있는 데 close bracket이 들어온 경우
        isBalanced = False
        break

  if(check or not isBalanced) :
    print("no")
  else :
    print("yes")