'$$x$$' is the product which is obtained from benzene by reacting it with carbon monoxide and hydrogen chloride in the presence of cuprous chloride. '$$y$$' is the major product obtained from the benzene by reacting it with ethanoyl chloride in the presence of anhydrous AlCl$$_3$$. Product (major) obtained by heating $$x$$ and $$y$$ in the presence of alkali is $$z$$. Total number of $$\pi$$ (pi) electrons in $$z$$ is __________.