Loop of length 12 starting with a string of length 6
found after enumerating 3256 derivations:

.cc.aaaa
	rule cc -> b at position 0
.b.aaaa
	rule ba -> aacb at position 0
.aacb.aaa
	rule ba -> aacb at position 3
.aacaacb.aa
	rule a ->  at position 3
.aacacb.aa
	rule a ->  at position 3
.aaccb.aa
	rule ba -> aacb at position 4
.aaccaacb.a
	rule ba -> aacb at position 7
.aaccaacaacb.
	rule a ->  at position 7
.aaccaacacb.
	rule a ->  at position 7
.aaccaaccb.
	rule cc -> b at position 6
.aaccaabb.
	rule b -> a at position 6
.aaccaaab.
	rule b -> a at position 7
.aaccaaaa.