if __name__ == '__main__':
    x = int(input())
    y = int(input())
    l = int(input())
    c = 0

    if x != 0:
        c += (abs(x) - 1) // l + 1
    if y != 0:
        c += (abs(y) - 1) // l + 1
    if y < 0:
        c += 2
    else:
        if x != 0:
            c += 1

    print(c)