Task: Question Answering
Input (English): Passage: The standard SNES controller adds two additional face buttons (X and Y) to the design of the NES iteration, arranging the four in a diamond shape, and introduces two shoulder buttons. It also features an ergonomic design by Lance Barr, later used for the NES-102 model controllers, also designed by Barr. The Japanese and PAL region versions incorporate the colors of the four action buttons into system's logo. The North American version's buttons are colored to match the redesigned console; the X and Y buttons are lavender with concave faces, and the A and B buttons are purple with convex faces. Several later consoles derive elements of their controller design from the SNES, including the PlayStation, Dreamcast, Xbox, and Wii Classic Controller. Question: How many shoulder buttons do SNES controllers have?
Output (English): two