You are given string *s* consists of opening and closing brackets of four kinds &lt;&gt;, {}, [], (). 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 &lt; by the bracket {, but you can't replace it by ) or &gt;.

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 *s*<sub class="lower-index">1</sub> and *s*<sub class="lower-index">2</sub> be a RBS then the strings &lt;*s*<sub class="lower-index">1</sub>&gt;*s*<sub class="lower-index">2</sub>, {*s*<sub class="lower-index">1</sub>}*s*<sub class="lower-index">2</sub>, [*s*<sub class="lower-index">1</sub>]*s*<sub class="lower-index">2</sub>, (*s*<sub class="lower-index">1</sub>)*s*<sub class="lower-index">2</sub> are also RBS.

For example the string "[[(){}]&lt;&gt;]" is RBS, but the strings "[)()" and "][()()" are not.

Determine the least number of replaces to make the string *s* RBS.
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 10<sup class="upper-index">6</sup>.
none
[<}){}
2
{()}[]
0
]]
Impossible
>
Impossible
{}
0
{}
0
{]
1
{]
1
{]
1
[]{[]({)([
Impossible
(([{>}{[{[)]]>>]
7
((<>)[]<]><]
3
[[([[(>]>)))[<)>
6
({)[}<)](}
5
(}{)[<][)(]}
6
>}({>]{[}<{<{{)[]]{)]>]]]<(][{)<<<{<<)>)()[>{<]]{}<>}}}}(>}<})(][>{((<{<)]}>)))][>[}[])<]){]]][<[)([
Impossible
<<[<{{<([({<<[)<>(]]){})>[](])[)))[[}>]<)>[[>{>>>[<]}<>>)[>]<{)<[><(<]][>(>]>][(<][{]}(()<[()[>><<])<]})]<]}{)
45
[<<{{((}[}<<)<)>})(][{>}})((>)<[)[>}[})[)>()[()[((}<<(>)<>](<>(}[>})[[[{)<}<<(}{>>}[<([[])<><)]<{>}[>>>{({>)}]})>)
42
(<[([(<({>(}{]>[(})])}])()<<}{]{[>]>(>>[(>>}[){(}<[{(()]{{<(<{][[{<><{<{)<>>]}}}{)(}{})}[<))>>}((({>){({}{{]}]>>}})>))
43
{(]}<([]<]{>]<{<({{{<>))}[({(}{)[}({>]}}<<)}<]))(<>(>{>{{{)<}({<]<>{)(>[)>{({}<([<[[)]><>{]}}(>]{}<)[})]}]]}]}>}
40
<(([)]<[}>{)>][[(<()({{{>>((]<}<{{<>}><<[)}[[)([[)[)}<]<{(<>){([)><{[([[][({])})<][(}]}>>[){)[({>){(}[}})>}>]>)]}))})>}]
45
)(
Impossible
[[[[[[[[
Impossible
# cook your dish here
if __name__ == "__main__":
    a = []
    s = input()
    s = list(s)
    # print(s)
    count = 0
    for i in range(len(s)):
        if s[i] == '<' or s[i] == '(' or s[i] == '{' or s[i] == '[':
            a.append(s[i])
        if(len(a) == 0):
            print("Impossible")
            break
        elif (s[i] == '>'  and a[-1] == '<') or (s[i] == ')' and a[-1] == '(') or (s[i] == '}' and a[-1] == '{') or (s[i] == ']' and  a[-1] == '['):
            a.pop()
        elif (s[i] == '>' and (a[-1] == '(' or a[-1] == '['or a[-1] == '{')):
            count = count + 1
            # print(a[-1])
            a.pop()
        elif (s[i] == ')' and (a[-1] == '<' or a[-1] == '['or a[-1] == '{')):
            count = count + 1
            # print(a[-1])
            a.pop()
        elif (s[i] == '}' and (a[-1] == '(' or a[-1] == '['or a[-1] == '<')):
            count = count + 1
            # print(a[-1])
            a.pop()
        elif (s[i] == ']' and (a[-1] == '(' or a[-1] == '<'or a[-1] == '{')):
            count = count + 1
            # print(a[-1])
            a.pop()
    if(len(a) == 0):
        pass
    else:
        print(count)
    
	    	 			  	   		     	 	    	