В соответствии к комментарию к ответу Andrio Skur:

words = ['a', 'asa1', 'dd', '111']
 
max_len_word = words[0]
 
for i in range(1, len(words)):
    word = words[i]
 
    if len(word) > len(max_len_word):
        max_len_word = word
 
print(max_len_word)  # asa1

Вот так:

def str_split(s):
  words = []
  buf = ''
  for char in s:
    if char == ' ':
      if buf:
        words.append(buf)
      buf = ''
    else:
      buf += char
  if buf:
    words.append(buf)
  return words
 
 
def words_print(words):
  for word in words:
    print(word)
 
 
def len_word(word):
  i = 0
  for _ in word:
    i += 1
  return i
 
 
def find_max(words):
  temp = 0, ''
  for word in words:
    word_length = len_word(word)
    if word_length > temp[0]:
      temp = word_length, word
  return temp[1]
 
 
words = str_split(input())
words_print(words)
print('Max:', find_max(words))