Consider the following three compounds (i)AX₂ₙⁿ⁻, (ii)AX₃ₙ and (ii)AX₄ₙⁿ⁺, where central atom A is 15th group element and their maximum covalency is 3n. If total number of proton in surrounding atom X is n and value of n is one, then calculate value of x³+y²+z² . (where x, y and z are total number of lone pair at central atom in compounds (i), (ii) and (iii) respectively.