Replace/pay for iphone exchange

Hello everyone! Just a simple question. A couple of months ago my iphone 5s (bought in january) got humidity and the screen (lcd) broke. I mean the screan is on and functional but you can see that it has weird marks anda spots. Im travelling to miami tomorrow (im from argentina) so im going to ask for an exchange. If they dont replace ir for free, the cost for a new iphone 5s is 260 dollars? Im are right?

Thanks