Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if:

1. Open brackets must be closed by the same type of brackets.
2. Open brackets must be closed in the correct order.
3. Every close bracket has a corresponding open bracket of the same type.

• A string s.

• Boolean value.

• 1 <= s.length <= 10^4
• s consists of parentheses characters only.

Input: s = "()[]{}"
Output: True