divide list ['a', 'b', 'c', '1', '2', '3'] into three separate list

def split(lst):
  a = [lst[i] for i in range(len(lst)) if lst[i] in 'abcABC']
    
  b = [lst[i] for i in range(len(lst)) if lst[i] not in 'abcABC']
    
  return a, b