Campaigns: Entering and Leaving?

Suppose I have a campaign based off a public segment. The campaign is a basic drip campaign that sends a series of 10 emails over a month.

After receiving 3 emails, the contact takes themselves out of a segment, but a week later, they add themselves back to the segment.

Do they start over from the first email? Or do they pick up where they left off?

Short answer: they start from step 1.
Long answer:

Regards: Joey