It is not clear if empty lines can be used in the input.
Is the next example possible?
<empty line>
5
#

Yes it possible.
A length of the string S doesn't exceed 100 symbols, but it not guaranteed not to be empty.

Extra hint for you:
try this:

-7293874219874982174982174987321E-18446744073709551616
10
#

Thank you, AterLux. That test is OK. I tried other tests from the forum. They are OK too. Anyway I have WA12.

Moreover, is the next example with just 2 lines possible?
#
1
It seems that it's possible. Do we have to write "Not a floating point number" because according to the statement we need to answer on each pair lines of the input?

That's hair-splitting
# means end of input, you need not to process this pair, also you need not to read second line in this pair.

My both AC solution (Pascal & Java) will not output anything with your example.

But, as we know, 12th test is not empty. When you get "Crash (Access violation)" - in most cases it mean reading or writing out of array bounds - so check it sizes.
check you can process 100-character string and can output 200-character at line

Be carefull with greatest numbers, + and - before numbers (and exponent too!),
check "Nafpn" answer for double -- or ++ or -+ and so on
also check you output 0.000 (without minus) when trimming -0.0000xxxx.