#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())

if(Y>0):
	ans = (Y+L-1)//L
	X = X if X > 0 else -X
	ans += (X+L-1)//L + 1 if X > 0 else 0
elif(Y==0):
	ans = 0
	X = X if X > 0 else -X
	ans += (X+L-1)//L + 1 if X > 0 else 0
else:
	ans = (-Y+L-1)//L
	X = X if X > 0 else -X
	ans += (X+L-1)//L + 2 if X > 0 else 2
print(ans)