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 PYTHON):

Solution:
string = str(raw_input())
answer = 0
good_seq = True
list_brackets = []
for i in range(len(string)):
	if string[i] == "<" or string[i] == "{" or string[i] == "[" or string[i] == "(":
		list_brackets.append(string[i])
	else:
		if list_brackets == []:
			good_seq = False
			break
		else:
			if not ((list_brackets[-1] == "<" and string[i] == ">")
				or (list_brackets[-1] == "{" and string[i] == "}")
				or (list_brackets[-1] == "[" and string[i] == "]")
				or (list_brackets[-1] == "(" and string[i] == ")")):
				answer += 1
			list_brackets.pop(-1)
if good_seq and list_brackets == []:
	print answer
else:
	print "Impossible"