PiauÃ shares borders with the states of MaranhÃ # o ( west ) , CearÃ ( east ) , Pernambuco ( east ) and Bahia ( east and south ) . PiauÃ is bounded on the west by MaranhÃ # o , on the east by CearÃ , Pernambuco and Bahia , and on the south by Tocantins .