Input: Read this: In non-relativistic classical mechanics, Newton's concept of "relative, apparent, and common time" can be used in the formulation of a prescription for the synchronization of clocks. Events seen by two different observers in motion relative to each other produce a mathematical concept of time that works sufficiently well for describing the everyday phenomena of most people's experience. In the late nineteenth century, physicists encountered problems with the classical understanding of time, in connection with the behavior of electricity and magnetism. Einstein resolved these problems by invoking a method of synchronizing clocks using the constant, finite speed of light as the maximum signal velocity. This led directly to the result that observers in motion relative to one another measure different elapsed times for the same event.
Question: The behavior of which two phenomena caused physicists to encounter problems with their understanding of clocks in the late 19th century?

Output: unanswerable


Input: Read this: Finally, an introduced species may unintentionally injure a species that depends on the species it replaces. In Belgium, Prunus spinosa from Eastern Europe leafs much sooner than its West European counterparts, disrupting the feeding habits of the Thecla betulae butterfly (which feeds on the leaves). Introducing new species often leaves endemic and other local species unable to compete with the exotic species and unable to survive. The exotic organisms may be predators, parasites, or may simply outcompete indigenous species for nutrients, water and light.
Question: Where does the Prunus spinosa leaf much sooner?

Output: In Belgium


Input: Read this: Hellenistic Geometers such as Archimedes (c. 287 – 212 BC), Apollonius of Perga (c. 262 – c. 190 BC), and Euclid (c. 325 – 265 BC), whose Elements became the most important textbook in mathematics until the 19th century, built upon the work of the Hellenic era Pythagoreans. Euclid developed proofs for the Pythagorean Theorem, for the infinitude of primes, and worked on the ﬁve Platonic solids. Eratosthenes used his knowledge of geometry to measure the circumference of the Earth. His calculation was remarkably accurate. He was also the first to calculate the tilt of the Earth's axis (again with remarkable accuracy). Additionally, he may have accurately calculated the distance from the Earth to the Sun and invented the leap day. Known as the "Father of Geography ", Eratosthenes also created the first map of the world incorporating parallels and meridians, based on the available geographical knowledge of the era.
Question: Who measured the circumference of the Earth?

Output: Eratosthenes


Input: Read this: In the 2005–06 season, Barcelona repeated their league and Supercup successes. The pinnacle of the league season arrived at the Santiago Bernabéu Stadium in a 3–0 win over Real Madrid. It was Frank Rijkaard's second victory at the Bernabéu, making him the first Barcelona manager to win there twice. Ronaldinho's performance was so impressive that after his second goal, which was Barcelona's third, some Real Madrid fans gave him a standing ovation. In the Champions League, Barcelona beat the English club Arsenal in the final. Trailing 1–0 to a 10-man Arsenal and with less than 15 minutes remaining, they came back to win 2–1, with substitute Henrik Larsson, in his final appearance for the club, setting up goals for Samuel Eto'o and fellow substitute Juliano Belletti, for the club's first European Cup victory in 14 years.
Question: Where did Barcelona defeat Real Madrid for a trophy win in 2005-06?

Output:
Santiago Bernabéu Stadium