Amos is taller than Eugene.  Leo is shorter than James but taller than Eugene.  James is shorter than Amos.  is the tallest andis the shortest. 
Overseas Competition->Knowledge Point->Counting Modules->Permutations and Combinations->Combinations
From clue $$2$$, James is taller than Leo and Leo is taller than Eugene.  From clue $$3$$, Amos is taller than James.  Rank from tallest to shortest: \textbf{Amos}, James, Leo, \textbf{Eugene}. 