Print the longest str from user input

[perfringo]

Some observations about your code:

- input is string, so no need to use str() for converting
- no need to define n before while loop. Use instead 'while True' and break
- use Larz60+ advice - append user answers to list and print out longest

As this is homework I provide 3.8-only compatible solution which probably will not pass automagic check but gives general idea:

values = []                                             # list to collect user entered strings
while (answer := input('Enter input: ')) != '':         # while loop which assigns user input to answer and checks equality to ''
    values.append(answer)                               # appends answers to values list

print(f'Longest input was {max(values, key=len)}')      # prints out longest element in values list