What's  sign at the beginning of my source file?

You propably save the files as UTF-8 with BOM. You should save them as UTF-8 without BOM.

It's called Byte Order Mark, and doesn't always have to be "". http://en.wikipedia.org/wiki/Byte_order_mark

Some Windows applications add BOM by default. In Notepad++ you can use some options in the Encoding menu like Encode in UTF without BOM or Convert to UTF without BOM.