Serious olympiad students keep a physical notebook of every problem they got wrong. Leminno makes it digital, automatic, and impossible to lose — with full context on every entry.
Every miss is tagged automatically — see at a glance that you're strong on AM-GM but keep tripping on SOS decomposition.
Add a note to any entry: "I forgot to check the p=2 case." The reflection is what makes a mistake stick.
Sort by hardest-first or unresolved-first, filter by topic, and find that one problem you keep meaning to revisit.
Wrong answers flow into spaced repetition (FSRS). The ones you fail come back sooner — until they're truly resolved.
The moment you miss a problem, it's logged with the statement, your answer, the correct approach, hints used, and time spent.
Add your own note while it's fresh. Naming the exact slip — "forgot the base case" — is what stops it happening again.
The problem returns on a spaced schedule. Get it right and it's marked resolved; miss it and it comes back sooner.
Every problem you practise feeds it automatically. Begin and watch your weak spots turn into strengths.