Self-joint Sudoku
Rules
Fill the grid with the digits from 1 to 9 so that each row, column and outlined area contains each digit exactly once. Also, all 3x3 regions are numbered from 1 to 9 in natural way row by row from the top left to the bottom right cell; if a digit in a cell has the same numerical value as its position, the cell is marked with grey, otherwise, it's white. All grey cells are given.
Click to see the answer.