Definition: In this task, you are given a news article. Your task is to classify the article to one out of the four topics 'World', 'Sports', 'Business', 'Sci/Tech' if the article's main topic is relevant to the world, sports, business, and science/technology, correspondingly. If you are not sure about the topic, choose the closest option. Note that URLs in the text have been replaced with [Link].
Input: Russian, US astronauts leave ISS on maintenance mission The Russian-US crew of the International Space Station (ISS) went on a five-hour space walk overnight to carry out maintenance work, Russian space officials said on Saturday, quoted by ITAR-TASS news agency.

Sci/Tech