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

An input string is valid if:

• Open brackets must be closed by the same type of brackets.
• Open brackets must be closed in the correct order.

Example 1:

Input: s = "()"
Output: True

Example 2:

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

Example 3:

Input: s = "(]"
Output: False

Example 4:

Input: s = "([)]"
Output: False