백준 4949 균형잡힌 세상

https://www.acmicpc.net/problem/4949

 

#백준 4949
#균형잡힌 세상


while True:
    stack = []
    S = input()
    if S == '.':
        break
    for i in S:
        if i == '(' or i == '[':
            stack.append(i)
        elif i == ')':
            if stack and stack[-1] == '(':
                stack.pop()
            else:
                stack.append(i)
                break
        elif i == ']':
            if stack and stack[-1] == '[':
                stack.pop()
            else:
                stack.append(i)
                break
    if stack:
        print('no')
    else:
        print('yes')