Integer Overflow/Underflow Analysis

Analyze the following contract for integer overflow and underflow vulnerabilities:

```
${{CONTRACT_CODE}}
```

Solidity Version: ${{SOLIDITY_VERSION}}

Please provide:
1. All arithmetic operations inventory
2. Vulnerable calculations identification
3. Exploitation scenarios for each vulnerability
4. Version-specific considerations:
   - Pre-0.8.0 SafeMath requirements
   - Post-0.8.0 built-in checks
   - Unchecked blocks analysis
5. Recommended fixes:
   - SafeMath implementation
   - Input validation
   - Bounds checking
6. Gas-efficient solutions
7. Test cases for edge cases

Include specific line references and fix recommendations.