PUMaC 2009 Geometry B Problem 7

Lines l and m are perpendicular. Line l partitions a convex polygon into two parts of equal area, and partitions the projection of the polygon onto m into two line segments of length a and b respectively. Determine the maximum value of \left\lfloor\frac{1000 a}{b}\right\rfloor. (The floor notation \lfloor x\rfloor denotes largest integer not exceeding x)