Example 7 The function $f(n)$ is defined on the set of positive integers and takes non-negative integer values, and for all $m, n$ we have
$$
\begin{aligned}
f(m+n)-f(m)-f(n) & =0 \text{ or } 1, \\
\text{and } f(2)=0, f(3)>0, f(9999) & =3333 .
\end{aligned}
$$

Find $f(1982)$.