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

count = 0

if Y >= 0:
	if X != 0:
		count += 1
else:
	count += 2

X = abs(X)
Y = abs(Y)

count = count + int(X / L) + int(Y / L)

if X % L != 0:
	count += 1
if Y % L != 0:
	count += 1

print(count)