Toggle Middle Bits

Write a Python function `toggle_middle_bits(n)` that toggles all the bits of a given integer `n` except the first and the last bits. The first and last bits remain unchanged, while all other bits are flipped (0 becomes 1 and 1 becomes 0).

#### Example Usage
```python [main.nopy]
print(toggle_middle_bits(9))  # Output: 15
print(toggle_middle_bits(10)) # Output: 12
print(toggle_middle_bits(11)) # Output: 13
print(toggle_middle_bits(0b1000001)) # Output: 0b1111111
print(toggle_middle_bits(0b1001101)) # Output: 0b1110011
```

#### Constraints
- Input `n` is a non-negative integer.
- The function should handle edge cases like `n = 0` or `n = 1` appropriately.
def toggle_middle_bits(n):
    """
    Toggle all bits of the number `n` except the first and last bits.

    Args:
        n (int): The input number.

    Returns:
        int: The number with middle bits toggled.
    """
    # Placeholder for the solution
    pass
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