Creating graph from sequential patterns and finding paths between nodes - neo4j

Question

I would like to create a graph model that captures the following sequential patterns and return unique paths between specific nodes:

Sequential Patterns

Pattern ID	Sequential Pattern
1	A8-->A9
2	A8-->S8-->A9
3	A8-->A9-->S9
4	A8-->S6-->S8
5	S8-->A8-->A9
6	A8-->S8-->S9

Edges of Graph Model

Edge ID	From Node	To Node	Type
1	A8	A9	-Transition->
2	A8	S8	-Transition->
3	S8	A9	-Transition->
4	A9	S9	-Transition->
5	A8	S6	-Transition->
6	S6	S8	-Transition->
7	S8	A8	-Transition->
8	S8	S9	-Transition->

The desired output of unique paths starting at A8 and ending at A9:

Path ID	Unique Path
1	A8-->A9
2	A8-->S8-->A9

I have tried the following:

MATCH (a: node{name:'A8'})
MATCH (b:node{name:'A9'})
CALL apoc.algo.allSimplePaths(a,b,'Transition>',3)
YIELD path
RETURN reduce(s="",n in nodes(path) | s+(CASE WHEN s="" THEN "" ELSE "-->" END) +n.name) as string

I get the following output:

string
A8-->A9
A8-->S8-->A9
A8-->S6-->S8-->A9 *
A8-->S9-->A9 *
A8-->S8-->S9-->A9 *
A8-->S6-->S9--A9 *

Any suggestions on how I can produce an output that excludes the last 4 paths (marked with *)?