import math, sequtils, strutils
var
  x: seq[int] = mapIt(0..2, stdin.readline.parseInt)
  ans: int = 0
if x[1] < 0:
  ans.inc 2
elif x[0] != 0:
  ans.inc
ans += (ceil(x[0].abs / x[2]) + ceil(x[1].abs / x[2])).int
echo ans