Consider the expression \( (a-1)^{\star}(((b+c) / 3)+d) \) . Let \( x \) be the minimum number of registers required by an optimal code generation (without any register spill) algorithm for a load/store architecture, in which(1) Only load and store instructions can have memory operand's and(2) Arithmetic instructions can have only register or rimmediate operands. The value of \( x \) is