It costs black one point. The cut is lethal: f4 pass g3... and there is no good reply left for black
so if black is first he plays f4, if white plays first she plays f4 and black has to cover the cut which cost him 1 point
(verberg) Houdt uw Postbus schoon door belangrijke berichten te archiveren en regelmatig de Verwijder-alle-berichtenknop in uw instellingen. (pauloaguia) (laat alle tips zien)