Sarika, Dev, and Rajiv are sharing a large block of cheese. They take turns cutting off one-third of what remains and eating it: first Sarika eats one-third of the cheese, then Dev eats one-third of the remaining amount, then Rajiv eats one-third of what remains, then back to Sarika, and so on. They stop when the cheese is too small to see. About what fraction of the original block of cheese does Sarika eat in total?