## Seven Coins Puzzle

Draw an {N/D} star polygon - a polygon whose N vertices are uniformly distributed on a circle, but are connected by counting the D-th neighbor. Regular polygons correspond to D = 1, and their symbol is usually abbreviated to {N}.

In the applet the symbol {N/D} appears in the lower right corner. Both numbers can be modified by clicking a little off their center lines. When N and D have a common factor, there are conflicting view points as to whether the configuration of nodes and edges represents a single polygon or a collection of polygons with fewer vertices. However, for the puzzle we shall assume that N and D are mutually prime. In the classical case, N = 8 and D = 3. The object is to place 7 coins (N - 1 in general) at the vertices of the star. A coin may only be placed by dragging the cursor along an edge from one vertex to another.

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Explanation