Thank you very much, your answer helped me to understand

Also, important: you must always use the return instruction a the end of your function. print has no effect (it just diplays stuff on the screen).

Hi. Please post in English (you can help yourself with an online translator if you need).

You must not use input here, nor call the function in your code. Just complete the code of the function. The tests call your function with different argument and check it returns the right answer.

Remove this:

num=int(input())
digital_root(num)

Answered.

Можливо я не зрозумів суті, але чому мені видає помилку EOFError: EOF when reading a line