题解 | #完成括号匹配#

def kuohaopipei(str):
    a = 0 # 需要添加的右括号数
    b = 0 # 需要添加的左括号数
    for char in str:
        if char == '[':
            a += 1
        elif char == ']':
            if a > 0:
                a -= 1
            else:
                b += 1
    result = '['*b + str +']'*a
    return result
str = input().strip()
print(kuohaopipei(str))