hdln dhln hldn lhdn dlhn ldhn hdnl dhnl hndl nhdl dnhl ndhl hlnd lhnd hnld nhld lnhd nlhd dlnh ldnh dnlh ndlh lndh nldh
Note: these 'words' (valid or invalid) are all the permutations of the word hdln. These words are obtained by scrambling the letters in hdln.