class Stack:
    def __init__(self):
        self.items = []
    def isEmpty(self):
        return self.items == []
    def push(self, item):
        self.items.append(item)
    def pop(self):
        return self.items.pop()
posible = True
cin = input()
a=Stack()
s=Stack()
for i in cin:
    if ( i == '(' or i == '[' or i == '{' ):
        s.push( i )

    if ( i == ')' or i == ']' or i == '}'):
        if s.isEmpty():
            a.push(i)
        else:
            temp = s.pop()
            if (i == ')' and temp != '(') or (i == ']' and temp != '[') or (i == '}' and temp != '{'):
                posible = False
                break
if posible:
    while not a.isEmpty():
        temp = a.pop()
        if temp == ']':
            temp = '['
        if temp == ')':
            temp = '('
        if temp == '}':
            temp = '{'
        print(temp, end = '')
    print(cin, end = '')
    while not s.isEmpty():
        temp = s.pop()
        if temp == '[':
            temp = ']'
        if temp == '(':
            temp = ')'
        if temp == '{':
            temp = '}'
        print(temp, end = '')
else:
    print('IMPOSSIBLE')