# coding: utf-8
import math
x = int(input())
y = int(input())
l = int(input())

ans = 0

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