def slope(p1, p2):
    if (p2[0] == p1[0]):
        return 0
    return ((p2[1] - p1[1]) / (p2[0] - p1[0]))
def slope(p1, p2):
    if (p2[0] == p1[0]):
        return 0
    return ((p2[1] - p1[1]) / (p2[0] - p1[0]))