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Iran MO (3rd Round)
2021 Iran MO (3rd Round)
2021 Iran MO (3rd Round)
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Iran MO (3rd Round)
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Arash and Babak L-corners squares
Arash and Babak play the following game, taking turns alternatively, on a
1400
×
1401
1400\times 1401
1400
×
1401
table. Arash starts and in his turns he colors
k
k
k
,
L
L
L
-corners (any three cell of a square). Babak in his turn colors one
2
×
2
2\times 2
2
×
2
square. Neither player is allowed to recolor any cell. Find all positive integers
k
k
k
for which Arash has a winning strategy.
3
4
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2
5
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1
4
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