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:
import sys

def judge(x):
    m = {'<':'>', '{':'}', '[':']', '(':')'}
    stack = []
    count = 0
    for ch in x:
        if ch in ['>', '}', ']', ')']:
            if len(stack) == 0:
                return -1
            if m[stack[-1]] != ch:
                count += 1
            stack.pop()
        else:
            stack.append(ch)
    if len(stack) > 0:
        return -1
    else:
        return count

get = sys.stdin.readline().strip()
out = judge(get)
if out > -1:
    print out
else:
    print "Impossible"