Author: Andrey Bogdanov
Fill in the grid with digits 1, 2, 3, 4 putting one digit per a cell. Two cells connected by the move of a chess knight cannot contain the same digit. Three identical digits cannot appear in consecutive cells horizontally, vertically or diagonally.
Grid control: Click at a cell reveals the value chooser. Click at the selected value changes the state of the cell. More details about grid control are at the help page.