Derivation tree and Productions from left most derivation of string

Question

How can one find Derivation tree and Productions of a Grammar from left-most derivation and string used?

I was given input string x = abaccacaa , left most derivation lder(x)=(1,2,1,3,4,1,3,5) and two rules :

1. Length of RHS of each production is 2
2. Each production's RHS starts with a terminal symbol

How should I go about solving this?