6	prefer	5	refer
5	frere	5	freer
4	reef	4	pree
4	perf	4	pere
4	peer	4	free
4	fere	3	rep
3	ref	3	ree
3	pre	3	per
3	pee	3	fer
3	fee	3	err
3	erf	3	ere
2	re	2	pe
2	fe	2	er
2	ef	2	ee