How Many Cities Have Riders Signed Up?

UrbanHop's expansion team reviews how far the rider base has spread, and the review always starts from a date: how many distinct cities have picked up a rider since then? An older start date takes in more of the history, while a recent one asks whether the last few weeks reached anywhere at all.

Riders

Input

The riders table above is already built for you — those rows are not read from input. What does arrive is a single line holding the start date of the review, written the same way signup_date writes its dates.

Task: Print how many distinct cities appear among riders whose signup_date falls on or after that date. If nobody signed up in that window, print 0.

Example: if the riders in the window came from seven cities, you'd print 7.