How do I count the number of new occurrences of a number in an array?

I have an array given as

x = [1 1 1 1 1 1 1 2 2 1 1 1 3 3 3 3 1 1 1 1 3 1 5]

I am trying to calculate how many new occurrences there are of the number 1. Importantly, this should ignore whether or how many times 1 recurs in the adjacent cell. In the above example, the answer would be 4, because there are 4 instances of 1 appearing, even though they differ in length.

Thanks!

Answer 1

[Paolo]

 nnz(diff([0 (x==1)])==1)