YES
O(n)
TRS:
 {f(f(a())) -> c()}
 DUP: We consider a non-duplicating system.
  Trs:
   {f(f(a())) -> c()}
  BOUND:
   Automaton:
    { a_0() -> 4,
     f_0(4) -> 3,
     f_0(3) -> 3,
      c_1() -> 5,
      c_0() -> 3,
          5 -> 3}
   Strict:
    {}
   Qed