YES(?,ELEMENTARY)

'epo* (timeout of 60.0 seconds)'
--------------------------------
Answer:           YES(?,ELEMENTARY)
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  add(0(), x) -> x
     , add(s(x), y) -> s(add(x, y))}

Proof Output:    
  Strict Rules in Predicative Notation:
   {  add(0(), x;) -> x
    , add(s(; x), y;) -> s(; add(x, y;))}
  Safe Mapping:
   safe(add) = {}, safe(0) = {}, safe(s) = {1}
  Argument Permutation:
   mu(add) = [1, 2]
  Precedence:
   add ~ add