Instruction: Parse the product information to locate the target attribute, and then provide the extracted value of the target attribute and its source in the output, specifying None if the attribute is not present.

Input:
Product title: Dell Inspiron 15R i15RMT-12441sLV 15.6-Inch Touchscreen Laptop (1.8 GHz Intel Core i7-4500U Processor, 16GB DDR3, 1TB HDD, Windows 8) Moon Silver [Discontinued By Manufacturer]
Product description: The new Inspiron 15R with 6-cell battery features up to 4th Gen Intel Core processors in a sleek design that's 17% thinner than the 2011 model. So you get all the performance you need, with a little more room in your bag for the other things that matter.
Product feature: Intel Core i7-4500U Processor 1.8 GHz, 16 GB DDR3L SDRAM, 1 TB 5400 rpm Hard Drive, 15.6-Inch Touchscreen Display
Product brand: Dell
Target attributes: Screen Size
Answer: attribute: screen size
value: 15.6-inch
source: product title
attribute: screen size
value: 15.6-inch
source: product feature