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:
### TEMPLATE BEGIN

from collections import defaultdict

def read_int():
    return int(raw_input())

def read_ints():
    return (int(x) for x in raw_input().split())

def read_int_list():
    return [int(x) for x in raw_input().split()]

def read_float():
    return float(raw_input())

def read_floats():
    return (float(x) for x in raw_input().split())

def read_float_list():
    return [float(x) for x in raw_input().split()]

def read_list():
    return [x for x in raw_input().split()]

### TEMPLATE END

s = raw_input()
stack = []
d = {'(': 0, '[':0, '<':0, '{':0, ')':1, ']':1, '>':1, '}':1}
match = {')':'(', ']':'[', '>':'<', '}':'{'}
modification = 0
impossible = False
for c in s:
    if d[c] == 0:
        stack.append(c)
    else:
        if not stack:
            print 'Impossible'
            impossible = True
            break
        else:
            cm = stack.pop()
            if match[c] != cm:
                modification += 1
if stack:
    print 'Impossible'
elif not impossible:
    print modification