46. On a highway, there is a grain warehouse every 50 kilometers, totaling 4 warehouses. Warehouse A has 10 tons of grain, Warehouse B has 20 tons of grain, Warehouse D has 50 tons of grain, and Warehouse C is empty. Now, all the grain needs to be centralized in one warehouse. If it costs 1 yuan to transport 1 ton of grain 1 kilometer, then the minimum cost would be $\qquad$ yuan for transportation.
Answer: 3500