Or if not display the exact input, at least give a hint as to what sort of input is causing the failure.

You're welcome! So glad I could be helpful. :)

I think this problem needs either a better explanation of the expected input (e.g., inputs will include only a string of letters and/or numbers surrounded by spaces, but there will be no spaces in between the numbers/letters), or better explanation as to what the expedcted output of, say, " 1 8 " or " 0 " would be.