Each row, column and region must contain the digits 1 to 9 once each. Each region is a set of 9 orthogonally connected cells and each region's position must be determined by the solver. Digits along an arrow sum to the digit in that arrow's circle. Digits may repeat along an arrow if allowed by other rules. Digits on an arrow (excluding its circle) have an equal sum N within each region it visits. It is possible that some arrows visit only one region. At any intersection between arrows, both arrows continue straight and they cannot overlap.