One day an unknown youth asked Mozart to explain to him how to start to compose a symphony.
- You are young, - answered Mozart. In the beginning write a ballade, and if you like it, come to me.
- But you! At the age of ten you have composed a lot of music.
- But I did not ask anybody how to do it.
Sudoku is played on a square field 9 by 9 of cells. The field itself is divided into regions (3 by 3 squares).
The goal of Sudoku is to fill all the empty cells with numbers 1-9 (one digit per cell), using the following rules:
1. The number can appear only once in each row.
2. The number can appear only once in each column.
3. The number can appear only once in each district.
Simply put, the same number can appear only once in each row, column and region.