So today I learnt a new thing, which I think will be useful for beginners. I thought that both of the lines are equivalent. However when I found out that the later is more efficient in case of sets.

set set1;

auto ite = upper_bound(set1.begin(), set1.end(), val); // O(n) // O(log n) in case of random access container. auto ite = set1.upper_bound(val);//O(log n) // binary search, uses set property

Hope this helps; return 0;