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:
def solve(s: str):
	stack = []

	answer = 0

	for c in s:
		if c in '([{<':
			stack.append(c)
		else:
			if not stack:
				print("Impossible")
				return

			b = stack[-1]
			if b == '(' and c != ')' or b == '[' and c != ']' or \
				b == '{' and c != '}' or b == '<' and c != '>':
				answer += 1;

			stack.pop()

	print("Impossible" if stack else answer)


if __name__ == '__main__':
	s = input()

	solve(s)