------
## 最终结论
```python
def count_unset_bits(n):
    total_bits = n.bit_length()  # Total number of bits required to represent n
    set_bits = bin(n).count('1')  # Count of set bits (1s)
    unset_bits = total_bits - set_bits  # Unset bits are total bits minus set bits
    return unset_bits

# Test cases
assert count_unset_bits(2) == 1
assert count_unset_bits(4) == 2
assert count_unset_bits(6) == 1
```