Rewrite this paragraph to be easier to understand:
Gian Giacomo Caprotti da Oreno, nicknamed Salai ̀ or Il Salaino (' The Little Unclean One ' i.e., the devil), entered Leonardo's household in 1490.
One of his young students was a boy whose name was Gian Giacomo Caprotti da Oreno. <SEP> But he was such a difficult and dishonest boy that Leonardo called him " Salai " or " Salaino " which means " the little devil ".