For the first subtask, we can brute force all pairs of lines.

Time Complexity: ~\mathcal{O}(N^2)~

For the second subtask, we can observe that two lines that have a different slope will always intersect. Two lines that have the same slope and the same ~y~-intercept will also always intersect (along the entirety of the line). Thus, the only pairs we need to find are the ones where the slope is the same and the ~y~-intercept is different. We can use a few hashmaps or maps for this. We can have one hashmap keep track of the number of lines with a certain slope, and another to keep track of the number of lines with a certain slope and a certain ~y~-intercept. Then, we can use inclusion-exclusion to calculate the number of pairs that never intersect.

Time Complexity: ~\mathcal{O}(N)~ or ~\mathcal{O}(N \log N)~