How many Olympian gods or goddesses are there?

as far as i no thair was 13

Hestia, Demeter, Dionysus, Hades, Apollo, Ares, Hermes, Hephaestus, Poseidon, Zeus, Aphrodite, Athena, Artemis,

the roman names were

Apollo, Mars, Mercury, Vulcan, Neptune, Jupiter, Venus, Minerva, Diana, Juno, Vesta, Ceres, Bacchus