Hint: the easiest way to code program is to incorporate $||($logical$-$or$)$ operation in the expression of the branching statements.

That is$,$ the outline of your program could be as follows:

if the order is increasing AND x is greater than y OR the order is decreasing AND x is less than y then

swap x and y

if the order is increasing AND y is greater than z OR the order is decreasing AND y is less than z then

swap y and z

if the order is increasing AND x is greater than y OR the oreder is decreasign AND x is less than y then

swap x and y again