Author: Andrey Bogdanov
Place all letters from the set (A,B,C,D,E) into the grid, so that each letter appears exactly once in each row and column. Some cells will remain empty. Letters outside show the first letters visible in the corresponding direction.
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.