Write a program (C#) that consists of several calculations to compute the area of different shapes provided. There are square, triangle, parallelogram and circle, user is given a menu to choose a desired shape. In your code, using of method overloading to computer the area of the chosen shape. To maintain the accuracy of result, a standard unit in centimetres (cm) need to be used. The program has to ensure all the user inputs are in appropriate unit for each shape.