Logic Masters Deutschland e.V.

Rules
Normal sudoku rules apply.
Digits along the red parity line must alternate between odd and even.
Additionally, this line acts as a thermometer: digits along it must increase from one end to the other (the solver must determine the direction).
In this puzzle, two orthogonally adjacent digits cannot have a difference of 7.
Draw a one-cell-wide loop of orthogonally connected cells. The loop may not touch itself, not even diagonally.
Every cell on the loop must contain an odd digit (but an odd digit is not necessarily on the loop).
Every odd digit on row 4 must be on the loop.
You must place exactly six 3s and six 5s on the loop.
You must place exactly six 4s inside the loop.

Play this puzzle on SudokuPad