How to derive $A$ from $A$ in First Order Logic

Question

I want to derive $A$ from $A$, here is what I have done :

0. A hypothese

1. $A$ (AA)

   1.1 $¬A$ (AA)

   1.2 $A$ (Negation Elimination from 1.1)

2. $A -> A$ (Introduction -> (1-1.2))

3. $A$ (MP(0,2))

Is this a good way to prove what I want ? Or I can't do that in derviation ?

Answer 1

Here is a one line proof:

0. A (hypothesis)

QED