X = int(input())
Y = int(input())
L = int(input())
i = 0

if X<0:
	X = X * -1
	i += 1
if Y<0:
	Y = Y * -1
if Y != 0:
	i += 1
	
i = i + (X//L + Y//L)

if X%L != 0:
	i = i + 1
if Y%L != 0:
	i = i + 1
print(i)