Rabin-Karp algorithm

For a set of strings and a hash function $h$, the number of collisions is the number of pairs of different strings with the same hash value for $h$. Consider all substrings of length 3 of a string $s = \textrm{ACACBAD}$. How many collisions does the polynomial hash function with $a = 3$ and $m = 11$ have for all these substrings?