x, y, l = STDIN.readlines.map(&:to_i)

terns = 0
terns += 1 if x.nonzero?
terns += 1 if y < 0
terns = 2  if x.zero? && y < 0

move_x = (x.abs / l.to_f).ceil
move_y = (y.abs / l.to_f).ceil

p terns + move_x + move_y