Difficult Combinatorics Problem, Help PLZ

i have this assignment due tmrw where i have to answer this question, plzzzzzzzz help i really dont understand it, im being marked for the process of thinking so steps will be very helpful

in a sequence of p zeroes and q ones, the ith term ti, is called a *change *point if ti does not equal ti-1, for i= 2,3,4....p+q. For example, the sequence of 0,1,1,0,1,0,1,0 has p=q=4, and five change points t2, t4, t6, t7, t8. For all possible sequences of p zeroes and q ones with 1 less then or equal to p which is less then or equal to q, determine the average number of change points.

i know its a difficult problem but plz jus try to help i really dont understand it!

(Yes)