# -*- coding: utf-8 -*-
x = int(input())
y = int(input())
l = int(input())
result = -1
if x==0 and 0<y:
    result=0
elif (0<x and 0<=y) or (x<0 and 0<y):
    result = 1
else:
    result = 2
x,y = abs(x), abs(y)

result += int(x/l) + int(y/l)
if x%l > 0:
    result += 1
if y%l > 0:
    result += 1
print(result)