Allowing users to edit only their page and nobody else’s

We currently have about 50 pages, each of which I want a user (eg, bob, rob, smith) to be able to edit only 1 page. For example, bob & smith each have their own page. I do not want bob to be able to edit smith’s page. I want bob to ONLY be able to edit bob’s page. I don’t care if he can see other pages.
Looking through the user roles, I don’t see a way to currently to do this- I only see how to allow restrict access on a global scale.