Write a program to read a number of units of length (a float) and print out the area of a circle of that radius. Assume that the value of pi is 3.14159 (an appropriate declaration will be given you by ceilidh - select setup). Your output should take the form: The area of a circle of radius ... units is units. If you want to be clever, and have looked ahead in the notes, print the message Error: Negative values not permitted. if the input value is negative. Exercise 12277