We need to improve the comments explaining the main ideas / insights of the solution

Describe the bug

When I try to swap lines with the command that CP Editor has configured in macOS (Command+Shift+(Up or Down Arrow)) it doesn't work, because in macOS, the shortcut Command+Up Arrow for example when used in text, moves the cursor from the current cursor position to the beginning, and Command+Down to the end

So when you also use Shift, what you get is that you select

Code one that runs in proportion to R instead of R and N (i.e. N should be able to be arbitrarily large)

See cpinitiative/usaco-guide#1087