Normal sudoku rules apply. Shade some cells to form a snake (a one-cell wide path that does not branch, cross itself or touch itself orthogonally. It can touch itself diagonally.) The snake consists entirely of odd digits and its head and tail are given by the grey circles. Clues outside the grid are skyscraper clues that ignore any snake cells in their row/column. ie Each digit that is not snake indicates the height of a building in that cell. Clues indicate the number of buildings that can be seen in their row/column from the side of the clue, where higher buildings obscure the view of lower buildings. Digits separated by an X sum to 10; digits separated by a V sum to 5. Not all Xs and Vs are necessarily given.