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:
import sys
s=input()
stack = []
c=0
cc=0
brackets = {')':'(',']':'[','}':'{','>':'<'}
for char in s:
    if char in brackets.values():
        stack.append(char)
        c=c+1
    elif char in brackets.keys():
        if stack==[]:
            print('Impossible')
            sys.exit()

        if brackets[char] != stack.pop() :
            cc=cc+1

        c=c-1
if c>0:
    print('Impossible')
    sys.exit()

'''
c=0
stack = []
brackets = {')':'(',']':'[','}':'{','>':'<'}
for char in s:
    if char in brackets.values():
        stack.append(char)
    elif char in brackets.keys():
        if brackets[char] != stack.pop():
            c=c+1
print(c)
'''
print(cc)