import sys
from collections import deque
input = sys.stdin.readline
while 1:
line = input().rstrip()
if line == '.':
break
is_balanced = True
stack = deque()
for char in line:
if not is_balanced:
break
if char not in ['[', ']', '(', ')']:
continue
if char in ['[', '(']:
stack.append(char)
continue
if not stack:
is_balanced = False
break
pop_item = stack.pop()
if char == ']':
if pop_item != '[':
is_balanced = False
break
continue
if char == ')':
if pop_item != '(':
is_balanced = False
break
continue
if is_balanced and (not stack):
print('yes')
else:
print('no')
