class Solution:
    def numberOfPairs(self, points: List[List[int]]) -> int:
        points.sort(key=lambda x: (x[0], -x[1]))
        res = 0
        for i, (_, y1) in enumerate(points):
            max_y = -inf
            for _, y2 in points[i + 1 :]:
                if max_y < y2 <= y1:
                    max_y = y2
                    res += 1
        return res