Problem: You are given string s consists of opening and closing brackets of four kinds <>, {}, [], (). There are two types of brackets: opening and closing. You can replace any bracket by another of the same type. For example, you can replace < by the bracket {, but you can't replace it by ) or >.

The following definition of a regular bracket sequence is well-known, so you can be familiar with it.

Let's define a regular bracket sequence (RBS). Empty string is RBS. Let s1 and s2 be a RBS then the strings <s1>s2, {s1}s2, [s1]s2, (s1)s2 are also RBS.

For example the string "[[(){}]<>]" is RBS, but the strings "[)()" and "][()()" are not.

Determine the least number of replaces to make the string s RBS.

Input

The only line contains a non empty string s, consisting of only opening and closing brackets of four kinds. The length of s does not exceed 106.

Output

If it's impossible to get RBS from s print Impossible.

Otherwise print the least number of replaces needed to get RBS from s.

Examples

Input

[&lt;}){}


Output

2

Input

{()}[]


Output

0

Input

]]


Output

Impossible

Solution (in PYTHON3):

Solution:
BRACKETS = "{ }, [ ], < >, ( )"
openers = dict()
closers = dict()
for opener, closer in map(lambda x: x.split(), BRACKETS.split(",")):
    openers[opener] = closer
    closers[closer] = opener
stack = list()
impossible = False
res = 0
for char in input():
    if char in openers:
        stack.append(char)
    else:
        if not stack:
            impossible = True
            break
        elif stack[-1] != closers[char]:
            res += 1
        stack.pop()
impossible |= len(stack) > 0
if impossible:
    print("Impossible")
else:
    print(res)