Complete the following proof outline

$\{$x $=$ X $$ y $=$ Y $>=0\}?\{$z $=$ XY $\}$

You should assume that variables x$,$ y$,$ and z hold mathematical

integers $$thus there is no overflow$$ and that the operations as$-$

signment, $+,-,\backslash$times $,-$:$,$odd$,$ and $$even$$ each take $1$ unit of time, as

do any comparisons. Be sure to state the invariant of your loop