Twin Sudoku is the next generation in the world of Sudoku puzzles. It is a composition of two regular sudoku grids sharing one set of 3 by 3 box or region.

Like any regular sudoku puzzle, each puzzle already contains some predetermined numbers in a fixed place. These numbers cannot be altered or changed. Your task is to fill in the blank squares.

The rules are the same as the rules when playing a regular sudoku.

• Each row must contain all numbers from 1 to 9
• Each column must contain the numbers from 1 to 9
• Each set of 3 by 3 box or region must contain the numbers 1 to 9
• Each number, from 1 to 9, must appear only once in each row, column, or region.

For Twin Sudoku there is one additional rule:

Numbers in the 3 by 3 box or region shared by the twins must be common or shared by both the Sudoku puzzles.

Finding a number in the shared set of 3 by 3 box or region means finding a clue to the further solution of both the twins.