Normal Sudoku Rules apply.
Arrow - Digits along an arrow sum to the circle.
Odd - grey circles are odd.
Friendly - Squares represent friendly cells.
Friendly cells contain a digit that equals their box number, row number, or column number.
There is also a single "buddy digit" for the puzzle.
All friendly cells must be orthogonally adjacent to this "buddy digit".
While the buddy digit is never marked with a square, all other friendly cells are marked with a square.
Any given digits are not the buddy digit, and the buddy digit is friendly 2 times.
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