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:
Martin_Luther

Context:
Luther's hymns were included in early Lutheran hymnals and spread the ideas of the Reformation. He supplied four of eight songs of the First Lutheran hymnal Achtliederbuch, 18 of 26 songs of the Erfurt Enchiridion, and 24 of the 32 songs in the first choral hymnal with settings by Johann Walter, Eyn geystlich Gesangk Buchleyn, all published in 1524.

Question:
How many hymns did Luther contribute to the Erfurt Enchiridion?

18