private static int entrance(List<Point> points){
        int size=points.size(),result=0;
        for(int i=0;i<size-1;++i){
            for(int j=i+1;j<size;++j){
                Point middle=middle(points.get(i),points.get(j));
                result=Math.max(result,inCircleCnt(middle,points));
            }
        }
        return result;
    }