Codility - Diamond Count

def solution(X, Y):
    points = set((x, y) for (x, y) in zip(X, Y))
    return sum(1 for p1 in points for p2 in filter(lambda p2: p2[0] < p1[0] and p2[1] < p1[1], points) if (2 * p1[0] - p2[0], p2[1]) in points and (p1[0], -p1[1] + 2 * p2[1]) in points)