import math
x = int(input())
y = int(input())
l = int(input())

if x == 0:
  if y >= 0:
    print(math.ceil(y/l))
  else:
    print(2 + math.ceil(abs(y)/l))
elif y == 0:
  if x >= 0:
    print(1 + math.ceil(x/l))
  else:
    print(1 + math.ceil(abs(x)/l))
elif x > 0 and y > 0:
  print(1 + math.ceil(y/l) + math.ceil(x/l))
elif x > 0 and y < 0:
  print(2 + math.ceil(x/l) + math.ceil(abs(y)/l))
elif x < 0 and y < 0:
  print(2 + math.ceil(abs(x)/l) + math.ceil(abs(y)/l))
else:
  print(1 + math.ceil(abs(x)/l) + math.ceil(y/l))