def main():
    x = int(input())
    y = int(input())
    l = int(input())

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

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

    print(ans)


if __name__ == "__main__":
    main()