pos(evs([])).
pos(evs([4,3])).
pos(evs([2,1,4,3])).
pos(evs([2,9,4,1,2,3])).
pos(evs([4,1,2,1,6,3,8,7])).
pos(evs([4,1,2,1,6,3,8,7,2,9,4,1,6,1,2,3])).

neg(evs([2,1,2,2])).
neg(evs([2,2,2,2])).
neg(evs([2,2,2,2,4,2,2,2,2])).
neg(evs([1,1,3])).
neg(evs([1,1,3,1])).
neg(evs([1,1,3,1,1])).
neg(evs([1,1,3,2])).
neg(evs([1,2])).
neg(evs([1])).