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
for ekbaar in range(1):
    s=str(input())
    while "[]" in s:
        s=s[:s.find("[]")]+s[s.find("[]")+2:]
    while "()" in s:
        s = s[:s.index("()")] + s[s.index("()")+2:]
    while "<>" in s:
        s = s[:s.index("<>")] + s[s.index("<>") + 2:]
    while "{}" in s:
        s = s[:s.index("{}")] + s[s.index("{}") + 2:]
    while "[]" in s:
        s = s[:s.find("[]")] + s[s.find("[]") + 2:]
    while "()" in s:
        s = s[:s.index("()")] + s[s.index("()") + 2:]
    while "<>" in s:
        s = s[:s.index("<>")] + s[s.index("<>") + 2:]
    while "{}" in s:
        s = s[:s.index("{}")] + s[s.index("{}") + 2:]
    while "[]" in s:
        s = s[:s.find("[]")] + s[s.find("[]") + 2:]
    while "()" in s:
        s = s[:s.index("()")] + s[s.index("()") + 2:]
    while "<>" in s:
        s = s[:s.index("<>")] + s[s.index("<>") + 2:]
    while "{}" in s:
        s = s[:s.index("{}")] + s[s.index("{}") + 2:]
    while "[]" in s:
        s = s[:s.find("[]")] + s[s.find("[]") + 2:]
    while "()" in s:
        s = s[:s.index("()")] + s[s.index("()") + 2:]
    while "<>" in s:
        s = s[:s.index("<>")] + s[s.index("<>") + 2:]
    while "{}" in s:
        s = s[:s.index("{}")] + s[s.index("{}") + 2:]
    while "[]" in s:
        s = s[:s.find("[]")] + s[s.find("[]") + 2:]
    while "()" in s:
        s = s[:s.index("()")] + s[s.index("()") + 2:]
    while "<>" in s:
        s = s[:s.index("<>")] + s[s.index("<>") + 2:]
    while "{}" in s:
        s = s[:s.index("{}")] + s[s.index("{}") + 2:]
    while "[]" in s:
        s = s[:s.find("[]")] + s[s.find("[]") + 2:]
    while "()" in s:
        s = s[:s.index("()")] + s[s.index("()") + 2:]
    while "<>" in s:
        s = s[:s.index("<>")] + s[s.index("<>") + 2:]
    while "{}" in s:
        s = s[:s.index("{}")] + s[s.index("{}") + 2:]
    while "[]" in s:
        s = s[:s.find("[]")] + s[s.find("[]") + 2:]
    while "()" in s:
        s = s[:s.index("()")] + s[s.index("()") + 2:]
    while "<>" in s:
        s = s[:s.index("<>")] + s[s.index("<>") + 2:]
    while "{}" in s:
        s = s[:s.index("{}")] + s[s.index("{}") + 2:]
    while "[]" in s:
        s = s[:s.find("[]")] + s[s.find("[]") + 2:]
    ans=0
    while "[>" in s:
        s=s[:s.find("[>")]+s[s.find("[>")+2:]
        ans+=1
    while "[}" in s:
        s = s[:s.find("[}")] + s[s.find("[}") + 2:]
        ans += 1
    while "[)" in s:
        s = s[:s.find("[)")] + s[s.find("[)") + 2:]
        ans += 1
    while "<}" in s:
        s = s[:s.find("<}")] + s[s.find("<}") + 2:]
        ans += 1
    while "<)" in s:
        s = s[:s.find("<)")] + s[s.find("<)") + 2:]
        ans += 1
    while "<]" in s:
        s = s[:s.find("<]")] + s[s.find("<]") + 2:]
        ans += 1
    while "{]" in s:
        s = s[:s.find("{]")] + s[s.find("{]") + 2:]
        ans += 1
    while "{)" in s:
        s = s[:s.find("{)")] + s[s.find("{)") + 2:]
        ans += 1
    while "{>" in s:
        s = s[:s.find("{>")] + s[s.find("{>") + 2:]
        ans += 1
    while "(]" in s:
        s = s[:s.find("(]")] + s[s.find("(]") + 2:]
        ans += 1
    while "(>" in s:
        s = s[:s.find("(>")] + s[s.find("(>") + 2:]
        ans += 1
    while "(}" in s:
        s = s[:s.find("(}")] + s[s.find("(}") + 2:]
        ans += 1
    while "()" in s:
        s = s[:s.index("()")] + s[s.index("()") + 2:]
    while "<>" in s:
        s = s[:s.index("<>")] + s[s.index("<>") + 2:]
    while "{}" in s:
        s = s[:s.index("{}")] + s[s.index("{}") + 2:]
    while "[]" in s:
        s = s[:s.find("[]")] + s[s.find("[]") + 2:]
    while "[>" in s:
        s = s[:s.find("[>")] + s[s.find("[>") + 2:]
        ans += 1
    while "[}" in s:
        s = s[:s.find("[}")] + s[s.find("[}") + 2:]
        ans += 1
    while "[)" in s:
        s = s[:s.find("[)")] + s[s.find("[)") + 2:]
        ans += 1
    while "<}" in s:
        s = s[:s.find("<}")] + s[s.find("<}") + 2:]
        ans += 1
    while "<)" in s:
        s = s[:s.find("<)")] + s[s.find("<)") + 2:]
        ans += 1
    while "<]" in s:
        s = s[:s.find("<]")] + s[s.find("<]") + 2:]
        ans += 1
    while "{]" in s:
        s = s[:s.find("{]")] + s[s.find("{]") + 2:]
        ans += 1
    while "{)" in s:
        s = s[:s.find("{)")] + s[s.find("{)") + 2:]
        ans += 1
    while "{>" in s:
        s = s[:s.find("{>")] + s[s.find("{>") + 2:]
        ans += 1
    while "(]" in s:
        s = s[:s.find("(]")] + s[s.find("(]") + 2:]
        ans += 1
    while "(>" in s:
        s = s[:s.find("(>")] + s[s.find("(>") + 2:]
        ans += 1
    while "(}" in s:
        s = s[:s.find("(}")] + s[s.find("(}") + 2:]
        ans += 1
    while "()" in s:
        s = s[:s.index("()")] + s[s.index("()") + 2:]
    while "<>" in s:
        s = s[:s.index("<>")] + s[s.index("<>") + 2:]
    while "{}" in s:
        s = s[:s.index("{}")] + s[s.index("{}") + 2:]
    while "[]" in s:
        s = s[:s.find("[]")] + s[s.find("[]") + 2:]
    while "[>" in s:
        s = s[:s.find("[>")] + s[s.find("[>") + 2:]
        ans += 1
    while "[}" in s:
        s = s[:s.find("[}")] + s[s.find("[}") + 2:]
        ans += 1
    while "[)" in s:
        s = s[:s.find("[)")] + s[s.find("[)") + 2:]
        ans += 1
    while "<}" in s:
        s = s[:s.find("<}")] + s[s.find("<}") + 2:]
        ans += 1
    while "<)" in s:
        s = s[:s.find("<)")] + s[s.find("<)") + 2:]
        ans += 1
    while "<]" in s:
        s = s[:s.find("<]")] + s[s.find("<]") + 2:]
        ans += 1
    while "{]" in s:
        s = s[:s.find("{]")] + s[s.find("{]") + 2:]
        ans += 1
    while "{)" in s:
        s = s[:s.find("{)")] + s[s.find("{)") + 2:]
        ans += 1
    while "{>" in s:
        s = s[:s.find("{>")] + s[s.find("{>") + 2:]
        ans += 1
    while "(]" in s:
        s = s[:s.find("(]")] + s[s.find("(]") + 2:]
        ans += 1
    while "(>" in s:
        s = s[:s.find("(>")] + s[s.find("(>") + 2:]
        ans += 1
    while "(}" in s:
        s = s[:s.find("(}")] + s[s.find("(}") + 2:]
        ans += 1
    while "()" in s:
        s = s[:s.index("()")] + s[s.index("()") + 2:]
    while "<>" in s:
        s = s[:s.index("<>")] + s[s.index("<>") + 2:]
    while "{}" in s:
        s = s[:s.index("{}")] + s[s.index("{}") + 2:]
    while "[]" in s:
        s = s[:s.find("[]")] + s[s.find("[]") + 2:]
    while "[>" in s:
        s = s[:s.find("[>")] + s[s.find("[>") + 2:]
        ans += 1
    while "[}" in s:
        s = s[:s.find("[}")] + s[s.find("[}") + 2:]
        ans += 1
    while "[)" in s:
        s = s[:s.find("[)")] + s[s.find("[)") + 2:]
        ans += 1
    while "<}" in s:
        s = s[:s.find("<}")] + s[s.find("<}") + 2:]
        ans += 1
    while "<)" in s:
        s = s[:s.find("<)")] + s[s.find("<)") + 2:]
        ans += 1
    while "<]" in s:
        s = s[:s.find("<]")] + s[s.find("<]") + 2:]
        ans += 1
    while "{]" in s:
        s = s[:s.find("{]")] + s[s.find("{]") + 2:]
        ans += 1
    while "{)" in s:
        s = s[:s.find("{)")] + s[s.find("{)") + 2:]
        ans += 1
    while "{>" in s:
        s = s[:s.find("{>")] + s[s.find("{>") + 2:]
        ans += 1
    while "(]" in s:
        s = s[:s.find("(]")] + s[s.find("(]") + 2:]
        ans += 1
    while "(>" in s:
        s = s[:s.find("(>")] + s[s.find("(>") + 2:]
        ans += 1
    while "(}" in s:
        s = s[:s.find("(}")] + s[s.find("(}") + 2:]
        ans += 1
    while "()" in s:
        s = s[:s.index("()")] + s[s.index("()") + 2:]
    while "<>" in s:
        s = s[:s.index("<>")] + s[s.index("<>") + 2:]
    while "{}" in s:
        s = s[:s.index("{}")] + s[s.index("{}") + 2:]
    while "[]" in s:
        s = s[:s.find("[]")] + s[s.find("[]") + 2:]
    while "[>" in s:
        s = s[:s.find("[>")] + s[s.find("[>") + 2:]
        ans += 1
    while "[}" in s:
        s = s[:s.find("[}")] + s[s.find("[}") + 2:]
        ans += 1
    while "[)" in s:
        s = s[:s.find("[)")] + s[s.find("[)") + 2:]
        ans += 1
    while "<}" in s:
        s = s[:s.find("<}")] + s[s.find("<}") + 2:]
        ans += 1
    while "<)" in s:
        s = s[:s.find("<)")] + s[s.find("<)") + 2:]
        ans += 1
    while "<]" in s:
        s = s[:s.find("<]")] + s[s.find("<]") + 2:]
        ans += 1
    while "{]" in s:
        s = s[:s.find("{]")] + s[s.find("{]") + 2:]
        ans += 1
    while "{)" in s:
        s = s[:s.find("{)")] + s[s.find("{)") + 2:]
        ans += 1
    while "{>" in s:
        s = s[:s.find("{>")] + s[s.find("{>") + 2:]
        ans += 1
    while "(]" in s:
        s = s[:s.find("(]")] + s[s.find("(]") + 2:]
        ans += 1
    while "(>" in s:
        s = s[:s.find("(>")] + s[s.find("(>") + 2:]
        ans += 1
    while "(}" in s:
        s = s[:s.find("(}")] + s[s.find("(}") + 2:]
        ans += 1
    while "()" in s:
        s = s[:s.index("()")] + s[s.index("()") + 2:]
    while "<>" in s:
        s = s[:s.index("<>")] + s[s.index("<>") + 2:]
    while "{}" in s:
        s = s[:s.index("{}")] + s[s.index("{}") + 2:]
    while "[]" in s:
        s = s[:s.find("[]")] + s[s.find("[]") + 2:]
    while "[>" in s:
        s = s[:s.find("[>")] + s[s.find("[>") + 2:]
        ans += 1
    while "[}" in s:
        s = s[:s.find("[}")] + s[s.find("[}") + 2:]
        ans += 1
    while "[)" in s:
        s = s[:s.find("[)")] + s[s.find("[)") + 2:]
        ans += 1
    while "<}" in s:
        s = s[:s.find("<}")] + s[s.find("<}") + 2:]
        ans += 1
    while "<)" in s:
        s = s[:s.find("<)")] + s[s.find("<)") + 2:]
        ans += 1
    while "<]" in s:
        s = s[:s.find("<]")] + s[s.find("<]") + 2:]
        ans += 1
    while "{]" in s:
        s = s[:s.find("{]")] + s[s.find("{]") + 2:]
        ans += 1
    while "{)" in s:
        s = s[:s.find("{)")] + s[s.find("{)") + 2:]
        ans += 1
    while "{>" in s:
        s = s[:s.find("{>")] + s[s.find("{>") + 2:]
        ans += 1
    while "(]" in s:
        s = s[:s.find("(]")] + s[s.find("(]") + 2:]
        ans += 1
    while "(>" in s:
        s = s[:s.find("(>")] + s[s.find("(>") + 2:]
        ans += 1
    while "(}" in s:
        s = s[:s.find("(}")] + s[s.find("(}") + 2:]
        ans += 1
    while "()" in s:
        s = s[:s.index("()")] + s[s.index("()") + 2:]
    while "<>" in s:
        s = s[:s.index("<>")] + s[s.index("<>") + 2:]
    while "{}" in s:
        s = s[:s.index("{}")] + s[s.index("{}") + 2:]
    while "[]" in s:
        s = s[:s.find("[]")] + s[s.find("[]") + 2:]
    while "[>" in s:
        s = s[:s.find("[>")] + s[s.find("[>") + 2:]
        ans += 1
    while "[}" in s:
        s = s[:s.find("[}")] + s[s.find("[}") + 2:]
        ans += 1
    while "[)" in s:
        s = s[:s.find("[)")] + s[s.find("[)") + 2:]
        ans += 1
    while "<}" in s:
        s = s[:s.find("<}")] + s[s.find("<}") + 2:]
        ans += 1
    while "<)" in s:
        s = s[:s.find("<)")] + s[s.find("<)") + 2:]
        ans += 1
    while "<]" in s:
        s = s[:s.find("<]")] + s[s.find("<]") + 2:]
        ans += 1
    while "{]" in s:
        s = s[:s.find("{]")] + s[s.find("{]") + 2:]
        ans += 1
    while "{)" in s:
        s = s[:s.find("{)")] + s[s.find("{)") + 2:]
        ans += 1
    while "{>" in s:
        s = s[:s.find("{>")] + s[s.find("{>") + 2:]
        ans += 1
    while "(]" in s:
        s = s[:s.find("(]")] + s[s.find("(]") + 2:]
        ans += 1
    while "(>" in s:
        s = s[:s.find("(>")] + s[s.find("(>") + 2:]
        ans += 1
    while "(}" in s:
        s = s[:s.find("(}")] + s[s.find("(}") + 2:]
        ans += 1
    while "()" in s:
        s = s[:s.index("()")] + s[s.index("()") + 2:]
    while "<>" in s:
        s = s[:s.index("<>")] + s[s.index("<>") + 2:]
    while "{}" in s:
        s = s[:s.index("{}")] + s[s.index("{}") + 2:]
    while "[]" in s:
        s = s[:s.find("[]")] + s[s.find("[]") + 2:]
    while "[>" in s:
        s = s[:s.find("[>")] + s[s.find("[>") + 2:]
        ans += 1
    while "[}" in s:
        s = s[:s.find("[}")] + s[s.find("[}") + 2:]
        ans += 1
    while "[)" in s:
        s = s[:s.find("[)")] + s[s.find("[)") + 2:]
        ans += 1
    while "<}" in s:
        s = s[:s.find("<}")] + s[s.find("<}") + 2:]
        ans += 1
    while "<)" in s:
        s = s[:s.find("<)")] + s[s.find("<)") + 2:]
        ans += 1
    while "<]" in s:
        s = s[:s.find("<]")] + s[s.find("<]") + 2:]
        ans += 1
    while "{]" in s:
        s = s[:s.find("{]")] + s[s.find("{]") + 2:]
        ans += 1
    while "{)" in s:
        s = s[:s.find("{)")] + s[s.find("{)") + 2:]
        ans += 1
    while "{>" in s:
        s = s[:s.find("{>")] + s[s.find("{>") + 2:]
        ans += 1
    while "(]" in s:
        s = s[:s.find("(]")] + s[s.find("(]") + 2:]
        ans += 1
    while "(>" in s:
        s = s[:s.find("(>")] + s[s.find("(>") + 2:]
        ans += 1
    while "(}" in s:
        s = s[:s.find("(}")] + s[s.find("(}") + 2:]
        ans += 1
    while "()" in s:
        s = s[:s.index("()")] + s[s.index("()") + 2:]
    while "<>" in s:
        s = s[:s.index("<>")] + s[s.index("<>") + 2:]
    while "{}" in s:
        s = s[:s.index("{}")] + s[s.index("{}") + 2:]
    while "[]" in s:
        s = s[:s.find("[]")] + s[s.find("[]") + 2:]
    if len(s)!=0:
        print("Impossible")
    else:
        print(ans)