4. The positive integer $n$ is less than 100, and satisfies the equation $\left[\frac{n}{2}\right]+\left[\frac{n}{3}\right]+\left[\frac{n}{6}\right]=n$, where $[x]$ denotes the greatest integer not exceeding $x$. How many such positive integers $n$ are there?
(A)2
(B) 3
(C) 12
(D) 16