I have a building, all four walls are 40' tall and 150 long. How much $ to pressure wash walls.?

I just need an idea at what kind of cost I'm looking at to have a company pressure wash all the wallsI have a building, all four walls are 40' tall and 150 long. How much $ to pressure wash walls.?
It depends on the condition of the building. Is it block, poured concrete etc. 40 feet is up there . Whoever does the they will probably need a lift. I wouldn't want to be on a ladder while using a pressure washer. Any way....figure on 20/45 cents per foot square