In this problem I used set < pair < int , int > > st;

auto it = lower_bound( st.begin(), st.end(), make_pair( a + d + 1 , 0 ) )

But it costs me several TLE. But when I look over the tutorial solution, I saw this-

it = st.lower_bound( make_pair( a + d + 1 , 0 ) );

I used it, & got AC.

But I don't understand what's the difference? If anyone can please help. TLE Submission AC Submission Thank You O_o