roofs orofs roofs orofs oorfs oorfs rofos orfos rfoos froos ofros foros rofos orfos rfoos froos ofros foros oofrs oofrs ofors foors ofors foors roosf orosf roosf orosf oorsf oorsf rosof orsof rsoof sroof osrof sorof rosof orsof rsoof sroof osrof sorof oosrf oosrf osorf soorf osorf soorf rofso orfso rfoso froso ofrso forso rosfo orsfo rsofo srofo osrfo sorfo rfsoo frsoo rsfoo srfoo fsroo sfroo ofsro fosro osfro sofro fsoro sforo rofso orfso rfoso froso ofrso forso rosfo orsfo rsofo srofo osrfo sorfo rfsoo frsoo rsfoo srfoo fsroo sfroo ofsro fosro osfro sofro fsoro sforo oofsr oofsr ofosr foosr ofosr foosr oosfr oosfr osofr soofr osofr soofr ofsor fosor osfor sofor fsoor sfoor ofsor fosor osfor sofor fsoor sfoor
Note: these 'words' (valid or invalid) are all the permutations of the word roofs. These words are obtained by scrambling the letters in roofs.