Instruction: Given the title, description, feature, price, and brand of a product and a set of target attributes, extract the value of each target attribute from the product information. Output the extracted value and the corresponding source (e.g., title or feature) denoting where the value is extracted.

Input:
Product title: Lenovo IdeaPad Y510p 15.6-Inch Laptop (Metal - Dusk Black)
Product description: Lenovo IdeaPad Y510p laptop
Product feature: Core i7-4700MQ 2.4 GHz (6 MB Cache), 1366 x 768 Display, 8 GB DDR3, 1000 GB 5400 rpm Hard Drive, 15.6-Inch Screen, NVIDIA GeForce GT750M GDDR5 2GB
Product price: $142.81
Product brand: Lenovo
Target attributes: Number of Cores
Answer: attribute: number of cores
value: None
source: None