Consider the following three compounds 
$\left(i\right)A{X}_{2n}^{n-} \left(ii\right)A{X}_{3n} \left(iii\right)A{X}_{4n}^{n+}$ , where central atom A is 15^th group element and their maximum covalency is  $3n.$  If total number of protons in surrounding atom  $X$ is $n.$  and value of  $n$  is one, then calculate value of  $"x^3+y^2+z".$ (Where  $x,y$ and $z$  are total number of lone pairs at central atom in compound  $\left(i\right),\left(ii\right)\&\left(iii\right)$ respectively.