Koburin #6
Colour the grey cells of the grid black or white, and draw a single closed line in the grid. The individual sections of the line run horizontally or vertically between the centres of orthogonally adjacent cells.
The number in a cell indicates the number of black cells that are orthogonally adjacent to this cell. There may also be black cells that are not adjacent to a number cell.
Cells with numbers cannot be blacked out. Two black squares must not be orthogonally adjacent. The line must run exactly once through all empty white cells (i.e., it cannot cross itself).