Enter a number between 0- and 10+
Kevin has decided that he enjoys + and -, but would like to retain a
10-point scale. This scale starts at 0- and includes 0+. Then each point
goes 1-, 1, 1+, 2-, etc. Up until 10+ which is in the inverse of 0 in
that it goes from 10- to 10+, marking the final point in this 33-point
scale.