Answer the question from the given passage. Your answer should be directly extracted from the passage, and it should be a single entity, name, or number, not a sentence.

Input: Consider Input: Passage: Chloroplasts have their own DNA, often abbreviated as ctDNA, or cpDNA. It is also known as the plastome. Its existence was first proved in 1962, and first sequenced in 1986—when two Japanese research teams sequenced the chloroplast DNA of liverwort and tobacco. Since then, hundreds of chloroplast DNAs from various species have been sequenced, but they're mostly those of land plants and green algae—glaucophytes, red algae, and other algal groups are extremely underrepresented, potentially introducing some bias in views of 'typical' chloroplast DNA structure and content. Question: When was the plastome discovered?

Output: 1962


Input: Consider Input: Passage: With International Criminal Court trial dates in 2013 for both President Kenyatta and Deputy President William Ruto related to the 2007 election aftermath, US President Barack Obama chose not to visit the country during his mid-2013 African trip. Later in the summer, Kenyatta visited China at the invitation of President Xi Jinping after a stop in Russia and not having visited the United States as president. In July 2015 Obama visited Kenya, as the first American president to visit the country while in office. Question: Where did Kenyatta visit at the invitation of the President?

Output: China


Input: Consider Input: Passage: A steam turbine consists of one or more rotors (rotating discs) mounted on a drive shaft, alternating with a series of stators (static discs) fixed to the turbine casing. The rotors have a propeller-like arrangement of blades at the outer edge. Steam acts upon these blades, producing rotary motion. The stator consists of a similar, but fixed, series of blades that serve to redirect the steam flow onto the next rotor stage. A steam turbine often exhausts into a surface condenser that provides a vacuum. The stages of a steam turbine are typically arranged to extract the maximum potential work from a specific velocity and pressure of steam, giving rise to a series of variably sized high- and low-pressure stages. Turbines are only efficient if they rotate at relatively high speed, therefore they are usually connected to reduction gearing to drive lower speed applications, such as a ship's propeller. In the vast majority of large electric generating stations, turbines are directly connected to generators with no reduction gearing. Typical speeds are 3600 revolutions per minute (RPM) in the USA with 60 Hertz power, 3000 RPM in Europe and other countries with 50 Hertz electric power systems. In nuclear power applications the turbines typically run at half these speeds, 1800 RPM and 1500 RPM. A turbine rotor is also only capable of providing power when rotating in one direction. Therefore, a reversing stage or gearbox is usually required where power is required in the opposite direction.[citation needed] Question: In the United States, what is a usual turbine speed with 60 Hertz of power?


Output: 3600 revolutions per minute


