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: N56VM-RB71 15.6" LED Notebook - Intel Core i7 i7-3610QM 2.30 GHz - Black Aluminum
Product description: ASUS COMPUTER
Product feature: N56VM-TB71, 8 GB, 750 GB, NVIDIA GeForce GT 630M
Product brand: Asus
Target attributes: Number of Cores
Answer: attribute: number of cores
value: None
source: None