State and prove loop measure:

$1//$ pre: a$,$b in Z

$2$ while $(($a $<10)($b $>2))$

$3$ if $($a is even$)$

$4$ a $$ a$+3$

$5$ b $$ b$+6$

$6$ else

$7$ a $$ a$-1$

$8$ b $$ b$-5$