import math

def main():
  dest_x = int(input())
  dest_y = int(input())
  move_limit = int(input())

  if dest_x == 0 and dest_y >= 0:
    turn = 0
  elif dest_x != 0 and dest_y >= 0:
    turn = 1
  else:
    turn = 2

  if dest_x == 0:
    move_x = 0
  else:
    move_x = math.ceil(abs(dest_x / move_limit))

  if dest_y == 0:
    move_y = 0
  else:
    move_y = math.ceil(abs(dest_y / move_limit))


  print(move_x + move_y + turn)

main()