def ceildiv(a: int, b: int) -> int:
    return (a + b - 1) // b


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


def y_cost():
    if Y >= 0:
        return ceildiv(Y, L)

    return ceildiv(abs(Y), L) + 2


def x_cost():
    if X == 0:
        return 0

    return ceildiv(abs(X), L) + 1


ans = x_cost() + y_cost()
print(ans)