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 JAVA):

Solution:
import java.util.*;
import java.io.*;
import java.math.*;
/**
 *
 * @author alanl
 */
public class Code {

    /**
     * @param args the command line arguments
     */
    static BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
    static StringTokenizer st;
    static PrintWriter pr = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
    public static void main(String[] args) throws IOException{
        String s = readLine();
        int ans = 0;
        Stack<Character>st = new Stack();
        Map<Character, Character>mp = new HashMap();
        mp.put('[', ']');
        mp.put('(', ')');
        mp.put('{', '}');
        mp.put('<', '>');
        for(int i = 0; i<s.length(); i++){
            char c = s.charAt(i);
            if(c=='(' || c=='{' || c=='<' || c=='['){
                st.push(c);
            }
            else{
                if(st.isEmpty()){
                    println("Impossible");
                    return;
                }
                if(c!=mp.get(st.peek())){
                    ans++;
                }
                st.pop();
            }
        }
        if(!st.isEmpty())println("Impossible");
        else println(ans);
    }
    static String next () throws IOException {
        while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(input.readLine().trim());
        return st.nextToken();
    }
    static long readLong () throws IOException {
        return Long.parseLong(next());
    }
    static int readInt () throws IOException {
        return Integer.parseInt(next());
    }
    static double readDouble () throws IOException {
        return Double.parseDouble(next());
    }
    static char readChar () throws IOException {
        return next().charAt(0);
    }
    static String readLine () throws IOException {
        return input.readLine().trim();
    }
    static void print(Object b) {
        System.out.print(b);
    }
    static void println(Object b) {
        System.out.println(b);
    }
    static void println() {
        System.out.println();
    }
}