Given a text passage, come up with an appropriate title for it. The title should accurately represent what the main focus of the passage is. The title of a passage may be present in the first few sentences of the passage and/or be referred to multiple times in the passage. The title should be 1-5 words long.

Example Input: St. Louis ( / sent lus / ) is an independent city and major U.S. port in the state of Missouri , built along the western bank of the Mississippi River , on the border with Illinois . The city had an estimated 2016 population of 311,404 , and is the cultural and economic center of the Greater St. Louis area ( home to 2,916,447 people ) , making it the largest metropolitan area in Missouri and the 19th - largest in the United States .
Example Output: St. Louis

Example Input: Transition state analogs ( transition state analogues ) , are chemical compounds with a chemical structure that resembles the transition state of a substrate molecule in an enzyme - catalyzed chemical reaction . Enzymes interact with a substrate by means of strain or distortions , moving the substrate towards the transition state . Transition state analogs can be used as inhibitors in enzyme - catalyzed reactions by blocking the active site of the enzyme . Theory suggests that enzyme inhibitors which resembled the transition state structure would bind more tightly to the enzyme than the actual substrate . Examples of drugs that are transition state analog inhibitors include flu medications such as the neuraminidase inhibitor oseltamivir and the HIV protease inhibitors saquinavir in the treatment of AIDS .
Example Output: Transition state analog

Example Input: The Secretary of State of California is the chief clerk of the U.S. State of California , overseeing a department of 500 people . The Secretary of State is elected for four year terms , like the state 's other constitutional officers , and is restricted by term limits to only two terms . The current Secretary of State , Alex Padilla , took office on January 5 , 2015 .
Example Output:
Secretary of State of California