x, y, l = [int(input()) for i in range(3)]
counter = 0

if x == 0 and y >= 0:
    counter += 0
elif y >= 0:
    counter += 1
elif y < 0:
    counter += 2

x, y = abs(x), abs(y)

if x != 0:
    counter += -(-x // l)

if y != 0:
    counter += -(-y // l)

print(counter)