In Greek mythology, how many gorgon sisters were there?

I know this is a bit cheesy but there was a fourth sister: Gorgon Zola.

I do believe that I use to date 2 of those girls, and I am sure the other one was my ex-wlfe.

I am not a number., hahahahaa

Medusa was a sister of the other two, however she was not born ugly. She was cursed. And I am personally disappointed that both Clash of the Titans movies has pegasus already existing. Pegasus was born from Medusa's blood after Perseus beheaded her. And he had help from both Athena and Hermes

there is a common number often having mystical associations.

I saw perseus beheaded Medusa and use her eyes to kill the monster

The never had wings