Nested Directory Structure Validator

You are given a string representing a nested directory structure where each directory is denoted by '/' and the base directory is indicated by a trailing '/'. Implement a function that determines if the directory structure is valid. The structure is valid if all directories open and close correctly without mismatched slashes. Output 'Valid' if the structure is valid, otherwise output 'Invalid'. Input Format: - A single string representing the nested directory structure. Output Format: - 'Valid' or 'Invalid'. Example: Input: //home/user/docs/ Output: Valid