delete unused parentheses

s = input()
stack = []
remove = set()

for i, ch in enumerate(s):
    if ch == '(':
        stack.append(i)
    elif ch == ')':
        if stack:
            stack.pop()
        else:
            remove.add(i)

remove.update(stack)

result = ""
for i in range(len(s)):
    if i not in remove:
        result += s[i]

print(result)