rail, 58 bytes

Result

WA

Code [DL]

$ 'dup'
 \
  \-(!a!)(a)(a)#

$ 'main'
 \
  \-[x]{dup}oo.#

stdin

2614229813859387064758680594224190761601526366564250472567485191716089205430991511994738685828455127

stdout

xx

stderr

Crash: No valid move

strace