import math

x = int(input())
y = int(input())
max_move_distance = int(input())

ans = 0
if y > 0:
  ans += max(math.ceil(y / max_move_distance), 1)
  if x != 0:
    ans += 1
    ans += max(math.ceil(abs(x) / max_move_distance), 1)
elif y == 0:
  if x != 0:
    ans += 1
    ans += max(math.ceil(abs(x) / max_move_distance), 1)
else:
  if x != 0:
    ans += max(math.ceil(abs(x) / max_move_distance), 1)
  ans += 2
  ans += max(math.ceil(abs(x) / max_move_distance), 1)
print(ans)