tic tac toe by rolf

import os;o=""
for c in os.read(0,99):o+=[c,"X"][len(o)in[[10],[8,14,34,39,53,67],[9,13,27,44]][id(0)%3]]
os.write(1,o)

Note that non-ascii characters in the above source code will be escaped (such as \x9f).

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