which returns the distance to the origen from the point (x,y).
Input
The input is formed by two reals
Observation
You only need to submit the required procedure;
your main program will be ignored.
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.