------
## 最终结论
```python
def Strongest_Extension(class_name, extensions):
    strongest_extension = ""
    strongest_strength = float('-inf')
    
    for extension in extensions:
        CAP = sum(1 for char in extension if char.isupper())
        SM = sum(1 for char in extension if char.islower())
        strength = CAP - SM
        
        if strength > strongest_strength:
            strongest_strength = strength
            strongest_extension = extension
            
    return f"{class_name}.{strongest_extension}"
```