x = int(input())
y = int(input())
d = int(input())

y1, y2 = divmod(y, d)
x1, x2 = divmod(x, d)
z = abs(y1) + y2 + abs(x1) + x2

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

print(z)