You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Doctor_Who

Context:
There have been instances of actors returning at later dates to reprise the role of their specific Doctor. In 1973's The Three Doctors, William Hartnell and Patrick Troughton returned alongside Jon Pertwee. For 1983's The Five Doctors, Troughton and Pertwee returned to star with Peter Davison, and Tom Baker appeared in previously unseen footage from the uncompleted Shada episode. For this episode, Richard Hurndall replaced William Hartnell. Patrick Troughton again returned in 1985's The Two Doctors with Colin Baker. In 2007, Peter Davison returned in the Children in Need short "Time Crash" alongside David Tennant, and most recently in 2013's 50th anniversary special episode, "The Day of the Doctor", David Tennant's Tenth Doctor appeared alongside Matt Smith as the Eleventh Doctor and John Hurt as the War Doctor, as well as brief footage from all of the previous actors. In addition, the Doctor has occasionally encountered himself in the form of his own incarnation, from the near future or past. The First Doctor encounters himself in the story The Space Museum (albeit frozen and as an exhibit), the Third Doctor encounters and interacts with himself in the story Day of the Daleks, the Fourth Doctor encounters and interacts with the future incarnation of himself (the 'Watcher') in the story Logopolis, the Ninth Doctor observes a former version of his current incarnation in "Father's Day", and the Eleventh Doctor briefly comes face to face with himself in "The Big Bang". In "The Almost People" the Doctor comes face-to-face with himself although it is found out that this incarnation is in fact just a flesh replica. In "The Name of the Doctor", the Eleventh Doctor meets an unknown incarnation of himself, whom he refers to as "his secret" and who is subsequently revealed to be the War Doctor.

Question:
What was the name of the 50th Anniversary episode?

The Day of the Doctor