P3084 [USACO13OPEN] Photo G

Farmer John has decided to assemble a panoramic photo of a lineup of his N cows (1

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There are 5 cows and 3 photos. The first photo contains cows 1 through 4, etc. From the last photo, we know that either cow 3 or cow 4 must be spotted. By choosing either of these, we satisfy the first two photos as well.