% Knight Noraml or Spy
% Three people: A,B,C, one spy, one knight, one normal
% spies lie, knights speak the truth, normals do both

perm([],[]).
perm(X,[Y|Z]):-select(X,Y,R),perm(R,Z).

says(k,P):- P.
says(s,P):- not P.
says(n,_).

problem(People):- People=[A,B,C], perm(People, [k,n,s]),
	says(A, C\=s),
	says(B, A\=k),
	says(C, B=k).