 So the parser should also use the rule "A" → "w" if ε is in Fi("w") and it sees on the input stream a symbol that could follow "A".Therefore, we also need the "Follow-set" of "A", written as Fo("A") here, which is defined as the set of terminals "a" such that there is a string of symbols "αAaβ" that can be derived from the start symbol.We use $ as a special terminal indicating end of input stream, and "S" as start symbol.