Intro to Summation (Σ) and Product (Π) Notation

Define a function $f:\mathbb{R} \to \mathbb{R}$ as follows: $$f(x) = \begin{cases} 1 &\text{if } x \text{ is divisible by 2} \\ -1 &\text{if } x \text{ is divisible by 3, but not by 2} \\ 0 &\text{otherwise} \end{cases}$$ What is the value of the following expression? $$\sum_{i=1}^{600}f(i)$$ (Hint: It might help to write out the first several values of $f(i)$.)