Answer 1

by following what the program is saying. 1 to add...
it will not work here in playground, because it's not an interactive console. you will have to add the inputs at once in new lines which is a mess.
try running your code on a computer or somewhere else that provides interactive console.
the code does not save anything after it closes. so you will see it only as long the program is running,
which again is not possible here because you can't hold the code running with the while loop here.