Dr. R. E. Wright's class was studying modified L-Systems. Let us explain necessary details. As a model let us have words of length n over a two letter alphabet {a, b}. The words are cyclic, this means we can write one word in any of n forms we receive by cyclic shift, whereby the first and the last letters in the word are considered to be neighbours.
Rewriting rules rewrite a letter at a position i, depending on letters at the positions i - 2, i, i+1. We rewrite all letters of the word in one step. When we have a given starting word and a set of rewriting rules a natural question is: how does the word look after s rewriting steps?
Help Dr. R. E. Wright and write a program which solves this task.