Sketchy Sudoku

A classic sudoku puzzle with sketchy look!
Drag and drop numbers to the appropriate fields.
If you make an error, a red frame will appear.
Tap 2 times on the number and it will disappear.
3 levels: easy, intermediate, hard.
Every sudoku puzzle can be solved with logic methods, so don't guess but think logically.
Light bulb button will help you if you get stuck but use it wisely, only when you really need it.