I have shaded some squares in the left-hand grid according to two simple rules:

Rule 1 – Squares that are next to each other, horizontally or vertically, cannot both be shaded.

Rule 2 – All the unshaded squares must be connected. In other words, you must be able to get from any unshaded square to any other unshaded square by moving horizontally or vertically through unshaded squares.

I have shaded 11 squares in the left-hand grid, but I can’t shade a 12th square without breaking the rules. For instance, shading the ‘E’ square would break rule 1, and shading the ‘3’ square would break rule 2 (as the ‘6’ and ‘8’ squares would be separated from the other unshaded squares).

However, if you start again, it is possible to shade 12 squares without breaking the rules. I have shaded two squares in the right-hand grid to start you off.

Which squares should you shade?