Teacher:In this task, you're given a passage, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.
Teacher: Now, understand the problem? Solve this instance: Passage: The Sierra Juarez is a range of mountains in Oaxaca state, Mexico between latitudes 1720'-1750'N and longitudes 9615'-9700'W, with an area of about 1,700km (656 sq mi). It is part of the Sierra Madre de Oaxaca. The range is separated from the Sierra de Zongolica to the north by the Santo Domingo River, flowing through the Tecomavaca Canyon. It stretches south-eastward to the Cajones River and the Sierra de Villa Alta. The mountains are in the district of Ixtlan de Juarez in the Sierra Norte de Oaxaca region. The range is named after Mexico's only indigenous president, Benito Juarez, who was born here in 1806 in the small village of San Pablo Guelatao. The heavily wooded area is about from the city of Oaxaca on Federal highway 175, heading towards Tuxtepec.
Link Information: none Question: How long is the Santo Domingo River?
Student:
Answer: none