Given the task definition and input, reply with output. In this task you will be given an answer to a question. You need to generate a question. The answer given should be a correct answer for the generated question.

Professor X is the founder of Xavier's School for Gifted Youngsters at a location commonly called the X-Mansion, which recruits mutants from around the world. Located in Westchester County, New York, the X-Mansion is the home and training site of the X-Men. The founding five members of the X-Men who appear in The X-Men #1 (September 1963) are Angel (Archangel), Beast, Cyclops, Iceman, and Marvel Girl (Jean Grey); Professor X and Magneto also made their first appearances in The X-Men #1. Since then, dozens of mutants from various countries and diverse backgrounds have held membership as X-Men.
who joined the x-men in x-men #1 from 1963