Input (grade 12): The System that is in use today is as follows: Whenever the same symbol is encountered four times, it is replaced by subtracing it from the next higher (/O5,50,500/O).
Output (grade 12): The System that is in use today is: Whenever the same symbol is written four times, it is replaced by subtracing it from the next higher number (/O5,50,500/O).