n = [0 for i in range(3)]
for i in range(3):
  n[i] = int(input())

cnt = 0

if n[1] >= 0:
  cnt += n[1] // n[2] + (1 if n[1] % n[2] != 0 else 0)
  if n[0] != 0:
    cnt += 1
    cnt += abs(n[0]) // n[2] + (1 if n[0] % n[2] != 0 else 0)
else:
  cnt += 1
  if n[0] != 0:
    cnt += abs(n[0]) // n[2] + (1 if n[0] % n[2] != 0 else 0)
  cnt += 1
  cnt += abs(n[1]) // n[2] + (1 if n[1] % n[2] != 0 else 0)

print('{}'.format(cnt))