divide this ['a', 'b', 'c', '1', '2', '3','4', '5', '6'] evenly into three separate list

lst =   ['a', 'b', 'c', '1', '2', '3','4', '5', '6']
def divide(lst):
  lst1 = []
  lst2 = []
  lst3 = []
  for i in lst:
    if i.isalpha():
      lst1.append(i)
    else:
      lst3.append(i)
  lst2 = lst1 + lst3
  return lst1, lst2, lst3

divide(lst)