Construct a turing machine (single taped) which reads in ,A,B with the input string consisting of {0, 1, 2, ,} and read/write head starts at the left most character (the comma before A). Allowed characters are {0, 1, 2, ,, ' ', $, a, b, c}. This turing machine will accept if A matches B. If accepted the output will be the ,A,B with the read/write head either at the left most character (comma before A) or right most character (last character in B).

Example of accepted input/output:

Input: ,210,210

Output: ,210,210

Input: ,111,111

Output: ,111,111

Example of rejected input/output:

Input: ,200,211

Input: ,102,222