1.start comapring digits from middle.
2.if rhs>lhs then increment middle digits by one using % operator.if digits have become zero carry on increment for next rhs and corrosponding lhs
3.for all other cond lhs=rhs
see test cases given on other message posting.good luck

if u have visited step2 once u need not visit it again only step3 is sufficient.best of luck.