You are playing the Regex Pattern Matcher game against claude 3.5 sonnet.

Game history:
Turn 1: claude 3.5 sonnet proposed text with target items: ["2023/12/25","01-15-2024","2024.03.15","2024/02/29","XY-123-AB99","YY-123-AB99","(123)","[456]","{789}"]
o3-mini - (low) provided pattern: ^(?:2023\/12\/25|01-15-2024|2024\.03\.15|2024\/02\/29|XY-123-AB99|YY-123-AB99|\(123\)|\[456\]|\{789\})$ (SUCCESS)

Current turn: 2 of 10
You are the PROPOSER.

Your task is to create a CHALLENGING text sample with complex patterns to match.
Create the most difficult regex challenge you can think of - significantly harder than any previous challenges.

Guidelines for creating a DIFFICULT challenge:
1. Use complex patterns that require advanced regex techniques to match.
2. Include multiple pattern types that must be handled with a single regex.
3. Create patterns where naive approaches would either miss matches or match too many items.
4. ADVANCED PATTERNS to consider:
   - Mixed formats (emails, phone n... (truncated)