COLUMBIA, Mo. (AP) — Columbia bus riders are competing this week in a citywide scavenger hunt.

The Columbia Missourian reports that Columbia Transit is asking riders to look for giant pictures of smartphones placed at bus stops each morning and afternoon this week.

The first person to find each picture's location will receive a four-month bus pass. And the first 50 people to post pictures of themselves at the bus stops to the Find 'N Ride Scavenger Hunt Facebook page will win one-month passes.

The scavenger hunt is part of an effort to promote a new DoubleMap smartphone app. DoubleMap shows a map of Columbia's bus routes, including football shuttles on game days.