Proof Writing & Problem Solving · Superchallenge problem

Define $T(1) = 0$ and, for $n \ge 2$, $T(n) = T(\lfloor n/2 \rfloor) + T(\lceil n/2 \rceil) + n - 1$. (This counts the comparisons merge sort makes in its worst case on $n$ items.) What is $T(1000)$?