import math
X = int(input())
Y = int(input())
L = int(input())

X_cnt = int(math.ceil(abs(X) / L))
Y_cnt = int(math.ceil(abs(Y) / L))
kaiten = 0

if X == 0 and Y >= 0:
    kaiten = 0
elif X != 0 and Y >= 0:
    kaiten = 1
else:
    kaiten = 2

print(X_cnt + Y_cnt + kaiten)