Hello! From what I could tell by looking at your code, you seem to be iterating through every possible pair of segments, checking for intersections, and then checking to see if the resulting graph is a tree. The problem is that iterating through every pair of intersections takes $$$O(n^2)$$$ time, which is way too much for $$$n < 5 \cdot 10^5.$$$ Could you find a more efficient way to find all pairs of intersections?