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:
#------------------Important Modules------------------#

from sys import stdin,stdout
from bisect import bisect_left as bl
from bisect import bisect_right as br
from heapq import *
input=stdin.readline
prin=stdout.write
from random import sample

from collections import Counter,deque
from math import sqrt,ceil,log2,gcd
#dist=[0]*(n+1)
mod=10**9+7
class DisjSet: 
    def __init__(self, n): 
        # Constructor to create and 
        # initialize sets of n items 
        self.rank = [1] * n 
        self.parent = [i for i in range(n)] 
  
  
    # Finds set of given item x 
    def find(self, x): 
          
        # Finds the representative of the set 
        # that x is an element of 
        if (self.parent[x] != x): 
              
            # if x is not the parent of itself 
            # Then x is not the representative of 
            # its set, 
            self.parent[x] = self.find(self.parent[x]) 
              
            # so we recursively call Find on its parent 
            # and move i's node directly under the 
            # representative of this set 
  
        return self.parent[x] 
  
  
    # Do union of two sets represented 
    # by x and y. 
    def union(self, x, y): 
          
        # Find current sets of x and y 
        xset = self.find(x) 
        yset = self.find(y) 
  
        # If they are already in same set 
        if xset == yset: 
            return
  
        # Put smaller ranked item under 
        # bigger ranked item if ranks are 
        # different 
        if self.rank[xset] < self.rank[yset]: 
            self.parent[xset] = yset 
  
        elif self.rank[xset] > self.rank[yset]: 
            self.parent[yset] = xset 
  
        # If ranks are same, then move y under 
        # x (doesn't matter which one goes where) 
        # and increment rank of x's tree 
        else: 
            self.parent[yset] = xset 
            self.rank[xset] = self.rank[xset] + 1
  
# Driver code 



def f(arr,i,j,d,dist):
    if i==j:
        return 
    nn=max(arr[i:j])
    for tl in range(i,j):
        if arr[tl]==nn:
            dist[tl]=d
            #print(tl,dist[tl])
            f(arr,i,tl,d+1,dist)
            f(arr,tl+1,j,d+1,dist)
    #return dist
            
        
def ps(n):
    cp=0;lk=0;arr=[];countprev=0;
    while n%2==0:
        n=n//2
        lk+=1
    
        
    for ps in range(3,ceil(sqrt(n))+1,2):
        lk=0
        while n%ps==0:
            n=n//ps
            lk+=1
            
            
    if n!=1:
        lk+=1
        return [lk,"NO"]
    
    
    return [lk,"YES"]


#count=0
#dp=[[0 for i in range(m)] for j in range(n)]
#[int(x) for x in input().strip().split()]
def gcd(x, y): 
      
    while(y): 
        x, y = y, x % y 
      
    return x 
          
# Driver Code         
def factorials(n,r):
    #This calculates ncr mod 10**9+7
    slr=n;dpr=r
    qlr=1;qs=1
    mod=10**9+7
    
    for ip in range(n-r+1,n+1):
        qlr=(qlr*ip)%mod
    for ij in range(1,r+1):
        qs=(qs*ij)%mod
    #print(qlr,qs)
    ans=(qlr*modInverse(qs))%mod
    return ans

        
        
def modInverse(b):
    qr=10**9+7
    return pow(b, qr - 2,qr)

#===============================================================================================
### START ITERATE RECURSION ###
from types import GeneratorType
def iterative(f, stack=[]):
  def wrapped_func(*args, **kwargs):
    if stack: return f(*args, **kwargs)
    to = f(*args, **kwargs)
    while True:
      if type(to) is GeneratorType:
        stack.append(to)
        to = next(to)
        continue
      stack.pop()
      if not stack: break
      to = stack[-1].send(to)
    return to
  return wrapped_func
def power(arr):
  listrep = arr
  subsets = []
  for i in range(2**len(listrep)):
    subset = []
    for k in range(len(listrep)):            
      if i & 1<<k:
        subset.append(listrep[k])
    subsets.append(subset)        
  return subsets
def dis(xa,ya,xb,yb):
    return sqrt((xa-xb)**2+(ya-yb)**2)
#### END ITERATE RECURSION ####
 
#===============================================================================================
#----------Input functions--------------------#
def ii():
    return int(input())
def ilist():
    return [int(x) for x in input().strip().split()]
def outstrlist(array:list)->str:
    array=[str(x) for x in array]
    return ' '.join(array);
def islist():
    return list(map(str,input().split().rstrip()))
def outfast(arr:list)->str:
    ss=''
    for ip in arr:
        ss+=str(ip)+' '
    return prin(ss);

###-------------------------CODE STARTS HERE--------------------------------###########
#########################################################################################
#t=int(input())
t=1
for jj in range(t):
    aa=input().strip()
    kk=[]
    ss={'<':0,'{':1,'[':2,'(':3,'>':4,'}':5,']':6,')':7}
    cc=0;bb=0
    for i in aa:
        if ss[i]<4:
            kk.append(ss[i])
        else:
            if len(kk)>0:
                if ss[i]-kk[-1]!=4:
                    cc+=1
                kk.pop();
            else:
                bb=1;break
    if bb==1 or len(kk)>0:
        print("Impossible")
    else:
        print(cc)