Super Sudoku

Sudoku games are getting more and more popular these days. Just grab a pen and a piece of paper and start solving various numeric puzzles. Various levels of difficulty for different groups of people. Easy one for puzzle beginners, medium for experienced puzzle solvers, and hard for real Sudoku enthusiasts! The goal is to write numbers from 1 to 9 into boxes in a way that no number will be occuring in both horizontal and vertical lines more than just once! This rule also applies for the smaller boxes, where you have to do the same, use each respective number just once! Can you solve the puzzle following these rules? Have fun.