# coding: utf-8
# Your code here!
import sys
read = sys.stdin.read
readline = sys.stdin.readline

x = int(readline())
y = int(readline())
L = int(readline())

ans = (abs(x)+L-1)//L + (abs(y)+L-1)//L

if y >= 0:
    if x != 0: ans += 1
else:
    ans += 2

print(ans)