Write a program that will take input from user, a sentence and find the number of words available in that sentence

def count_words(sentence):
  words = 0
  for word in sentence.split():
    if word not in stopwords:
      words += 1
  return words

def main():
  # read the file
  with open('./input.txt') as f:
    sentences = f.read().splitlines()

  # count the words
  total_words