The upper and lower bound, as well as the Big O have to do with the loops. The questions to ask are which loops do you have in your code? How many times does each loop run in the worst case and best case scenarios? If a loop contains another loop, you multiply their best cases and their worst cases.
For your particular program, there is one loop, and it goes from 0 to n-1. There is no early out so your best case, worst case, and average case all have the same value.
That would be "n" operations, so O(n), Ω(n) and ø(n).