Don't lie. My gut feeling has never failed me. Okay, 23. Does that work?
Here's my plan: You meet with Metropolitan Joe - a 22-year-old mage with short black hair, gray eyes, and a gray cloak. You invite him to a tavern under the pretext of waiting for an important ally from the emperor. And there you drink with him to the health of the emperor, under the guise of a signal to an agent of the empire. The stakes are 23 silver coins! and free drinks! The rest is already prepared."