Problem 1: Write a function that sorts the content of a generic stack according to user input. If the user enters 0 , the stack is sorted in ascending order (element at top is the smallest and element at bottom is the largest) and if the user enters 1 the stack is sorted in descending order. Problem 2: Write a function that shuffles the content of an odd-sized vector around the center element. Your function should prompt an error for even-sized vector. Problem 3: Overload operator +0 to enable adding two equally sized stacks. - In all parts, assume variable size containers (stack and vector) - Test your implementation in main()