#coding: UTF-8

import sys
from math import pi
from collections import deque
from functools import reduce

### defs ###

### main ###
X = int(sys.stdin.readline())
Y = int(sys.stdin.readline())
L = int(sys.stdin.readline())

ans = 0 if Y >= 0 else 1
X = X if X >= 0 else -X
Y = Y if Y >= 0 else -Y
ans += (Y+L-1)//L if Y>0 else 0
ans += (X+L-1)//L + 1 if X > 0 else 0
print(ans)