Normal sudoku rules apply. Draw a one-cell-wide loop of orthogonally connected cells. The loop may not touch itself, not even diagonally. The loop acts as a parity line: digits along the loop must alternate between even and odd digits. Digits along an arrow must sum to the digit in that arrow's bulb, and all bulbs are on the loop. Additionally, arrow tips point towards a cell containing the digit within the arrow's bulb, and this cell with the pointed-to digit is also on the loop. The digit in the arrow tip indicates the distance from the arrow tip to the pointed-to cell. There may be other instances of the same digit between this cell and the arrow tip.