My solution works fine on my test cases,
what's wrong about this problem?
if the input is 1,which one is the correct output?
case 1: 1
case 2: 11
case 3: ?

The answer to your question is certainly "1" (I see no
ambiguity).
As far as I understand, the joke is in "print '-1'" instead
of "print ' 1'" (that is what my browser shows).
Also note that output for N=0 is not -1
P.S. Remember Pell's equation? :)

> The answer to your question is certainly "1" (I see no
> ambiguity).
> As far as I understand, the joke is in "print '-1'"
instead
> of "print ' 1'" (that is what my browser shows).
what do you mean "print '-1'?
in my browser,it shows "print '?'"

> Also note that output for N=0 is not -1
> P.S. Remember Pell's equation? :)

> The answer to your question is certainly "1" (I see no
> ambiguity).
> As far as I understand, the joke is in "print '-1'"
instead
> of "print ' 1'" (that is what my browser shows).
> Also note that output for N=0 is not -1
> P.S. Remember Pell's equation? :)
yes,i remember you,:-)
thanks for your help again.

> > As far as I understand, the joke is in "print '-1'"
> instead
> > of "print ' 1'" (that is what my browser shows).
> what do you mean "print '-1'?
> in my browser,it shows "print '?'

I don't think any program that prints something other than
MINUS ONE in case the required number does not exist will
ever be accepted.

> > > As far as I understand, the joke is in "print '-1'"
> > instead
> > > of "print ' 1'" (that is what my browser shows).
> > what do you mean "print '-1'?
> > in my browser,it shows "print '?'
>
> I don't think any program that prints something other than
> MINUS ONE in case the required number does not exist will
> ever be accepted.
Thanks lyubshin,i got accepted.

> > > As far as I understand, the joke is in "print '-1'"
> > instead
> > > of "print ' 1'" (that is what my browser shows).
> > what do you mean "print '-1'?
> > in my browser,it shows "print '?'
>
> I don't think any program that prints something other than
> MINUS ONE in case the required number does not exist will
> ever be accepted.
I got accepted.
thanks lyubshin again...

in my brower , it says you should print '?' if such a
number doesn't exist, so I got wrong answer again and again,
then I see your message, and changed language in browser,
now it's print -1,

How should I hate the Internet Explorer, Though I always
use it!