ผู้ชนะประเภทภูเขา Carlos Sastre เมื่อประเภททั่วไปคือ Denis Menchov?
What's the mountains classification of winner Carlos Sastre when the general classification is Denis Menchov?
df = pd.DataFrame(columns=['mountains_classification', 'general_classification', 'winner'])
df.loc[(df['general_classification'] == 'denis menchov') & (df['winner'] == 'carlos sastre'), 'mountains_classification']