4 4  ## unordered bitrades of size 9
abcd dcab
bca` abc`
d``b b``d
```` ````

abc` bca`
bca` cab`
cab` abc`
```` ````

abc` cab`
da`b ab`d
c`bd d`cb
```` ````

Generated 3 bitrades from 5 
A complete list.