u/EnderMar1oo

Title, I'm about to take part in the Italian Math Olympiad and I was wondering if I need to prove LTE from the ground up if I need it for an exercise or if it's usually considered to be a "basic" lemma, much like other number theory theorems. I remember reading somewhere that LTE is famous enough for graders to recognise it, but at the same time it's not elementary enough to be mentioned without any sort of accessory explanation; writing down its complete proof during a competition seems like too much of a hassle though...