Normal sudoku rules apply. Digits along an arrow must sum to the number in the circle. There is one 1-cell-wide snake (with a head and a tail) that enters each box exactly once. It may not touch itself, not even diagonally. The number in any circle indicates how many cells the snake occupies in that box. The first two digits on the arrow, as read from the circle, give a 2-digit number showing the sum of the snake's cells in the circle's box.