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
import java.util.ArrayList;
import java.util.Scanner;

public class CodeForces132 {
  public static void main(String argv[]) {
    Scanner scanner = new Scanner(System.in);
    
    String s1 = scanner.nextLine();
    char[] ch = s1.toCharArray();
    
    boolean impossible = false;
    int left = 0;
    int right = 0;

    ArrayList<char[]> start = new ArrayList<>();
    ArrayList<char[]> fin = new ArrayList<>();
    
    for(int i = 0; i < ch.length; i++) {
      if(ch[i] == '{') {
        char[] char1 = new char[2];
        char1[0] = '{';
        start.add(char1);
        left++;
      } 
      else if(ch[i] == '(') {
        char[] char1 = new char[2];
        char1[0] = '(';
        start.add(char1);
        left++;
      }
      else if(ch[i] == '<') {
        char[] char1 = new char[2];
        char1[0] = '<';
        start.add(char1);
        left++;
      }
      else if(ch[i] == '[') {
        char[] char1 = new char[2];
        char1[0] = '[';
        start.add(char1);
        left++;
      }
      else if(start.size() == 0) {
        impossible = true;
        break;
      }
      else if(ch[i] == '}') {
        char[] char1 = start.get(start.size() - 1);
        char1[1] = '}';
        fin.add(char1);
        start.remove(start.size() - 1);
        right++;
      }
      else if(ch[i] == ')') {
        char[] char1 = start.get(start.size() - 1);
        char1[1] = ')';
        fin.add(char1);
        start.remove(start.size() - 1);
        right++;
      }
      else if(ch[i] == ']') {
        char[] char1 = start.get(start.size() - 1);
        char1[1] = ']';
        fin.add(char1);
        start.remove(start.size() - 1);
        right++;
      }
      else if(ch[i] == '>') {
        char[] char1 = start.get(start.size() - 1);
        char1[1] = '>';
        fin.add(char1);
        start.remove(start.size() - 1);
        right++;
      }
      if(right > left) {
        impossible = true;
        break;
      }
    }
    
    if(right != left) {
      impossible = true;
    }
    
    int total = 0;
    
    for(int i = 0; i < fin.size(); i++) {
      if(fin.get(i)[1] - (fin.get(i)[0]) != 1 && fin.get(i)[1] - (fin.get(i)[0]) != 2) {
        total++;
      }
    }
    
    if(impossible) {
      System.out.println("Impossible");
    } else {
      System.out.println(total);
    }
    
    scanner.close();
  }
}
