Puzzle 223: Divided in one

This is a Nikoli puzzle,known popularly as Nanro.
Rules: Write a number in some of the white cells.Each bordered region will contain one or more same numbers.The numbers indicate how many cells in that region are filled.No 2x2 area may be completely occupied by numbers.In the end, all numbers must be reachable from one another horizontally or vertically.If two orthogonally adjacent cells contain the same number,they cannot belong to different regions.