Normal sudoku rules apply. Draw 4 snakes, moving orthogonally through the grid. Snakes may not move diagonally, branch, enter cages, cross themselves, or share cells with each other. But they may touch themselves and each other in any way they like. Each circled digit lies at one end of a snake, and indicates how many marked 3x3 boxes that snake visits. Digits in a cage sum to the clue in the corner (if one is given.) Digits separated by an X sum to 10. Digits separated by a black dot are in a 1:2 ratio (one is double the other.) Each snake follows ONE AND ONLY ONE of the four rules below (breaking all the other rules at least once.) Each snake follows a different rule. • ALTERNATING PARITY: Digits along the snake alternate between odd and even. • GERMAN WHISPER: Adjacent digits have a difference of at least 5. • PALINDROME: The snake reads the same in either direction. • NON-VENOMOUS: No pair of adjacent digits anywhere along the snake sum to exactly the 'venom value'. The venom value (which is the same for any snake) is to be deduced.