A device consists of 4n elements, any two of which are joined by
either a red or a blue wire. The numbers of red and blue wires are
the same. The device is disabled by removing two wires of the same
color connecting four di
erent elements. Prove that the number of
ways to disable the device by removing two blue wires is the same
as the number of ways by removing two red wires.
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UP 0 DOWN 0 2 0
