import math

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