For a lab we must convert an infix expression to a postfix one that is devoid of parentheses.

Like if I entered (3 + 5) the postfix expression is 35+

However, what if I do (19 + 2)? It certainly is not 192+, for that would make 111, which just... isn't right. And we can't do (19)2+ I assume because the problem clearly states that parenthesis cannot be used. What's the official way, here?