ตำแหน่ง G จากสหรัฐอเมริกาถูกร่างเป็น Pick 13 ในรอบใดในปี 1971-1 1971
In which round was Position G  from the United States drafted as Pick 13 in 1971-1 1971?
df = pd.DataFrame(columns=['round', 'draft', 'pick', 'nationality', 'position'])
df.loc[(df['nationality'] == 'United States') & (df['position'] == 'G') & (df['pick'] == '13') & (df['draft'] == '1971-1 1971'), 'round']