How do I print words that are the same in two sentences in python?

Question

5a. Prompt the user to enter 2 sentences, called sen1 and sen2

5b. Print all the words that are in both sentences

Answer 1

sen1 = (input("Input first sentence: ").split(" "))
sen2 = (input("input second sentence: ").split(" "))
print(list(set(sen1).intersection(sen2)))

Answer 2

Sorry I misunderstand your question at first. This is the corrected version. (PS: I did not consider the sentence initial situation, you may use lower() function to correct the code yourself.

def main():
    sen1 = input('Please enter sentence 1:')
    sen2 = input('Please enter sentence 2:')
    wordlist1 = a1.split()
    wordlist2 = a2.split()   
    for i in wordlist1:
        if i in wordlist2:
            print(i)
        else:
            print('No common word.')
main()