niffs inffs nfifs fnifs ifnfs finfs niffs inffs nfifs fnifs ifnfs finfs nffis fnfis nffis fnfis ffnis ffnis iffns fifns iffns fifns ffins ffins nifsf infsf nfisf fnisf ifnsf finsf nisff insff nsiff sniff isnff sinff nfsif fnsif nsfif snfif fsnif sfnif ifsnf fisnf isfnf sifnf fsinf sfinf nifsf infsf nfisf fnisf ifnsf finsf nisff insff nsiff sniff isnff sinff nfsif fnsif nsfif snfif fsnif sfnif ifsnf fisnf isfnf sifnf fsinf sfinf nffsi fnfsi nffsi fnfsi ffnsi ffnsi nfsfi fnsfi nsffi snffi fsnfi sfnfi nfsfi fnsfi nsffi snffi fsnfi sfnfi ffsni ffsni fsfni sffni fsfni sffni iffsn fifsn iffsn fifsn ffisn ffisn ifsfn fisfn isffn siffn fsifn sfifn ifsfn fisfn isffn siffn fsifn sfifn ffsin ffsin fsfin sffin fsfin sffin
Note: these 'words' (valid or invalid) are all the permutations of the word niffs. These words are obtained by scrambling the letters in niffs.