Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE staff_department_assignments (department_id VARCHAR)
### Question:
What is the id of the department with the least number of staff?
### Answer:
SELECT department_id FROM staff_department_assignments GROUP BY department_id ORDER BY COUNT(*) LIMIT 1