Goal:
  
  n : t
  a : t
  l : list t
  IHl : forall m : t, n <= m \/ Exists (le n) l -> n <= fold_left max l m
  m : t
  H0 : n <= a
  ============================
   (n <= max m a \/ Exists (le n) l)


DEBUG:Going to execute:
left
DEBUG LTAC Evaluated term: IHl