x = int(input())
y = int(input())
l = int(input())
count = 0
if y < 0:
  count += 2
elif x >= 1 or x < 0:
  count += 1

x = abs(x)
y = abs(y)

if x <= l and not x == 0:
  count += 1
elif x % l == 0:
  count += x / l
else:
  count += x // l + x % l

if y <= l and not y == 0:
  count += 1
elif y % l == 0:
  count = y / l
else:
  count += y // l + y % l

print(int(count))