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: Oscar Schmidt OG2CESMG Spalted Maple Acoustic-Electric Guitar - Gold Tuners
Product description: The OG2CE is a deep dreadnought cutaway with a full acoustic resonance. It features a preamp with digital tuner built in. Now available with gold tuners!
Product feature: Spalted maple top, Active EQ system with built-in tuner, Rosewood fretboard and bridge, Fully adjustable truss rod, Available with exclusive gold tuners!
Product brand: Oscar Schmidt
Target attributes: Number of Strings
Answer: attribute: number of strings
value: None
source: None