Several distinct positive integers no larger than $$10$$ are listed in a row. After inspecting the row of numbers, Mark concluded with astonishment that in each pair of adjacent numbers one is a divisor of the other. At most how many numbers are in the list? ． 
Overseas Competition->Knowledge Point->Combinatorics->Strategies and Operations->Operational Problem
$$6$$, $$3$$, $$9$$, $$1$$, $$4$$, $$8$$, $$2$$, $$10$$, $$5$$. Only $$7$$, which is a prime number and doesn\textquotesingle t have multiples except itself among $$1$$\textasciitilde$$10$$, doesn\textquotesingle t appear. 