The azul sky out the windows puts on in the mind of a beach in Mexico. How many windows? Uno, dos, tres, quatro!
Rules:
Normal Sudoku rules apply.
Digits within circles appear at least once in cells touching the circle.
Windoku: There are four additional regions marked in blue. Each also contains the digits 1 through 9.
Estimated difficulty: 1.5 out of 5
Solve on SudokuPad