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

if Y < 0:
	i = i + 2
	if X < 0:
		i -= 1
	Y = Y * -1
if X != 0:
	i += 1
	if X < 0:
		X = X * -1
	
i = i + (X//L + Y//L)

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