%const p=1.  -- 2 persons
%const n=3.  -- 4 floors

person(0).
person(1).

floor(0).
floor(1).
floor(2).
floor(3).

initially(origin(0,3)).
initially(destination(0,2)).

initially(origin(1,1)).
initially(destination(1,3)).

initially(lift_at(0)).

initially(neg(boarded(P))):- person(P).

initially(neg(served(P))):- person(P).