Author: Vladimir Portugalov
Place a number from 1 to 8 in each empty cell in the grid such that each row, column and marked area contains each number exactly once. The clues outside the grid indicate the sum of the first X numbers placed in the corresponding direction, where X is equal to the first number placed in that 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.