Give an algorithm that takes as input a positive integer n and a number x, and computes x^2 (i.e., x raised to the power n) by performing O(lg n) multiplications. Your algorithm CANNOT use the exponentiation operation, and may use only the basic arithmetic operations (addition, subtraction, multiplication, division, modulo). Moreover, the total number of basic arithmetic operations use should be O(lg n). (Hint, Use divide and conquer).