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: Nord Electro 5D 73 Velocity Sensitive 73-Key Semi-Weighted Waterfall Keyboard (NELECTRO5D-73)
Product description: With greatly expanded memory, the added ability to split and layer and a live focused program section, the Nord Electro 5 is a highly refined, focused, yet flexible stage keyboard. The Electro 5 Organ section features an additional Principal Pipe Organ mode as well as the C2D B3 Tone Wheel simulation and the highly acclaimed Rotary Speaker simulation of a vintage 122 unit from the award winning Nord C2D Combo Organ. The Farfisa and Vox organ models are just as impressive as the B3, simulating the behavior and unique response of the original instruments. Both the Electro 5D 61/5D 73 feature physical Drawbars and can accommodate the Nord Half-Moon switch with stop/slow/fast modes (sold separately). The new Electro 5 series features 1GB of Piano Sample memory, allowing you to bring even more of Nord's unique sampled acoustic and electric pianos on stage. The subtle but effective Sympathetic String Resonance technology is implemented in the Electro 5, delivering an unprecedented degree of realism to your performance when using the Grand or Upright pianos. The Electro 5 features a dedicated Sample Synth section with expanded memory for the Nord Sample Library (256 MB) and additional controls for attack, decay/release and dynamics (filter/velocity). The included Nord Sample Editor makes it possible to add any sound you want to your Electro 5. The Nord Electro 5 Effect section features great, tweak able effects for instantly adding some dirt, glimmer or atmosphere to your sound, plus all effects are now in Stereo. The Amp/Speaker simulation features the same Vintage 122 Rotary Speaker simulations as found in the Nord C2D. There's also a flexible Stereo Delay effect with Tap-Tempo and Ping-Pong mode. The Nord Electro 5 has two sound slots that can be combined in a layer or split over the keyboard. Each of the sound slots can have specific effects, Control Pedal and/or Sustain Pedal assigned to them. The split function includes 6 split points, indicated with LED lights.
Product feature: 73-key semi-weighted waterfall keyboard, 1 GB Nord Piano library; 256 MB Nord Sample library, Large OLED display for excellent overview and readability, Physical drawbars to manipulate your sound in real-time, 6 Split Points with LED indicators, Splits and Layers Piano/Organ, Piano/Sample, Sample/Organ, 1 GB memory for Nord Piano Library, 256 MB memory for Nord Sample Library, OLED Display for excellent overview and readability, 6 Split Points with LED indicators
Product price: $2,199.00
Product brand: Nord
Target attributes: Number of Keys
Answer: attribute: number of keys
value: 73
source: product title
attribute: number of keys
value: 73-key semi-weighted waterfall keyboard
source: product feature
attribute: number of keys
value: 73-key semi-weighted waterfall keyboard
source: product title
attribute: number of keys
value: keyboard (nelectro5d-73
source: product title
attribute: number of keys
value: 73 velocity sensitive 73-key semi-weighted waterfall keyboard
source: product title