def main():
    x = int(input())
    y = int(input())
    l = int(input())
    step_x = 0
    step_y = 0

    def step(a):
        if abs(a) % l == 0:
            steps = abs(a) / l
        else:
            steps = abs(a) / l + 1
        return int(steps)

    if y >= 0:
        ans = step(y) + step(x) + 1
    else:
        ans = step(y) + step(x) + 2

    print(ans)


if __name__ == "__main__":
    main()