from math import ceil


def main():
    X = int(input())
    Y = int(input())
    L = int(input())

    move_num = 0
    if X != 0:
        move_num += 1
    if Y < 0:
        move_num += 1

    move_num += ceil(abs(Y / L))
    move_num += ceil(abs(X / L))
    print(move_num)


if __name__ == "__main__":
    main()