RULE
Fill in the grid so that each row, each column and each block contains all the numbers 1 through 9.
LEVEL
A puzzle's level is determined by the most advanced skill necessary to solve it:
- EasySingleton, Hidden Single in block
- MediumHidden Single in line/column, Naked Single
- HardIntersection, Hidden/Naked Pair
- ExpertHidden/Naked Triplet/Quad, Fish, XY/Z-Wing, Uniqueness
- MasterChains