The first question:
When n= 1, S= 1, T= 1.
When n=2 and S=3, T= 1+2.
When n >; 2, S=2n, t = 1+n+2+1+…+1,where the number of1after 2 is n-3.
For example, when n=5, S= 10, t =1+5+2+1+.
The second question:
The answer to the first question also applies. It's just a waste of the advantages of the ring