In the country of Xan there are three classes of people:
Knights who always tell the truth.
Knaves who always lie and
Jesters who sometimes tell the truth and sometimes lie.
Alan, Brian, Calvin and Guillermo are 4 inhabitants of Xan. Alan says: "There are 3 knights among us." Brian says: "There are 3 knights among us." Calvin says: "There are 2 knights among us." And Guillermo says: "There are no knights among us."
What kind of person is Guillermo?