Nested JSON Keys Count

Given a nested JSON object, count the total number of keys present at all levels. You must consider that some keys may contain objects as values which, in turn, can contain more keys. The input will be provided as a string representation of a JSON object. You should output a single integer indicating the total count of unique keys encountered. Input Format: - A single line containing a string representation of a JSON object. Output Format: - A single integer representing the total count of unique keys. Example: Input: {"a": 1, "b": {"c": 2, "a": 3}, "d": {"e": {"f": 4}}} Output: 5