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:
SYMBOLS={'}':'{',']':'[',')':'(','>':'<'}
SYMBOLS_L,SYMBOLS_R=SYMBOLS.values(),SYMBOLS.keys()



arr=[]
num=0
left=0
right=0
flag=True
s=input()
for c in s:
    if c in SYMBOLS_L:
        arr.append(c)
        left+=1
    elif c in SYMBOLS_R:
        right+=1
        if len(arr) == 0:
            flag=False
            break
        elif arr[-1] == SYMBOLS[c]:
            arr.pop()
        else:
            num+=1
            arr.pop()

if right!=left:
    flag=False
if flag:
    print(num)
else:
    print('Impossible')