import math
x = int(input())
y = int(input())
l = int(input())
p = 0
if x == 0 and y > 0:
    p = 0
elif y > 0:
    p = 1
elif y < 0:
    p = 2

cnt = math.ceil(abs(x)/l) + math.ceil(abs(y)/l) + p
print(cnt)