https://dogpa0130.medium.com/python-practice-1-%E9%96%8B%E5%95%9F%E6%8C%87%E5%AE%9A%E7%B6%B2%E9%A0%81%E6%90%9C%E5%B0%8B%E4%B8%89%E5%A4%A7%E9%9B%BB%E4%BF%A1%E5%95%86%E9%80%9A%E8%A8%8A%E8%A6%86%E8%93%8B%E7%8E%87-f7080e4fb67