------
## 最终结论
```python
def starts_one_ends(n):
    if n < 1:
        return 0
    
    # Count of n-digit numbers that start with 1
    start_with_1 = 10**(n - 1)  # From 10^(n-1) to 19... (n-1 times)
    
    # Count of n-digit numbers that end with 1
    end_with_1 = 9 * (10**(n - 2)) if n > 1 else 1  # From (10^(n-2)) to (9...(n-2 times)1)
    
    # Count of n-digit numbers that start and end with 1
    start_and_end_with_1 = 10**(n - 2) if n > 1 else 0
    
    return start_with_1 + end_with_1 - start_and_end_with_1
```