Sukoro

Sukoro is a Japanese logic puzzle. Write a number in some cells so that each number indicates how many numbers are adjacent to it.

Rules: In some cells of the grid, you must enter a number from 1 to 4. The number in a cell indicates how many number cells are orthogonally adjacent to that cell.
Equal numbers cannot be orthogonally adjacent. All number cells must form a single, orthogonally contiguous area.