import math

x = int(input())
y = int(input())
l = int(input())

distance = 0
distance += math.ceil(abs(x) / l)
distance += math.ceil(abs(y) / l)

if x < 0 and y < 0:
    distance += 2
else:
    if x < 0:
        distance += 1
    if y < 0:
        distance += 2

print(distance)