รายชื่อโรงเรียนที่ไม่มีทุนสนับสนุนใดๆ
List the names of the schools without any endowment.
endowment = pd.DataFrame(columns=['school_name', 'school_id']); school = pd.DataFrame(columns=['school_name', 'school_id'])
school.loc[~school['school_id'].isin(endowment['school_id'])]['school_name']