import math

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

ans = 0

if y >= 0 and abs(x) > 0:
  ans += 1
elif y < 0:
  ans += 2

ans += math.ceil(abs(x) / max_move_distance)
ans += math.ceil(abs(y) / max_move_distance)

print(ans)