graph TD A[Raw CSV Input] --> B[Task 1: Initial Data Validation] B --> C[Task 2: Data Format Normalization] C --> D[Task 3: Final CSV Structure Validation] D --> E[Clean CSV Output] B --> F[Remove Duplicates] B --> G[Validate Required Fields] B --> H[Remove Incomplete Records] C --> I[Standardize Phone Numbers] C --> J[Normalize City Names] C --> K[Trim Whitespace] D --> L[Verify Column Order] D --> M[Check Data Completeness] D --> N[Format Final CSV] F --> C G --> C H --> C I --> D J --> D K --> D L --> E M --> E N --> E