In the following Finite Accepters the initial state is indicated by the label "start", and any final states are indicated by their box being checked as shown below. start s0 inital state final state Given the following finite accepter, what's the alphabet of its language? s0 S2 start s1 S3 (write your answers in terms of just the characters that form the alphabet, sorted in alphabetical or numerical order without spaces or anything else)