Aldehydes Ketones And Carboxylic Acids

' $x$ ' 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 $\mathrm{AlCl}_3$. Product (major) obtained by heating $x$ and $y$ in the presence of alkali is $z$. Total number of $\pi$ (pi) electrons in $z$ is $\_\_\_\_$ .