Fix one station as selected. By rotational symmetry, fix station 1. Then the two neighbors (8 and 2) cannot be selected. We choose 2 more from stations 3, 4, 5, 6, 7, with no two adjacent (since 4 and 5 are adjacent, etc.), and no adjacency to 1 or each other.

Sun, 03 May 2026 01:11:55 +0000

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