que retorna la distància a l’origen del punt (x,y).
Entrada
L’entrada consisteix en dos reals.
Observació
Només cal enviar el procediment demanat;
el programa principal serà ignorat.
About statements
The official statement of a problem is always the one
in the PDF document. The HTML version of the statement
is also given to help you, but may contain some content
that is not well displayed. In case of doubt, always use the PDF.