###Answer the question from the input provided. Please answer from input only.

###Input: Tesla's demonstration of his induction motor and Westinghouse's subsequent licensing of the patent, both in 1888, put Tesla firmly on the "AC" side of the so-called "War of Currents," an electrical distribution battle being waged between Thomas Edison and George Westinghouse that had been simmering since Westinghouse's first AC system in 1886 and had reached the point of all-out warfare by 1888. This started out as a competition between rival lighting systems with Edison holding all the patents for DC and the incandescent light and Westinghouse using his own patented AC system to power arc lights as well as incandescent lamps of a slightly different design to get around the Edison patent. The acquisition of a feasible AC motor gave Westinghouse a key patent in building a completely integrated AC system, but the financial strain of buying up patents and hiring the engineers needed to build it meant development of Tesla's motor had to be put on hold for a while. The competition resulted in Edison Machine Works pursuing AC development in 1890 and by 1892 Thomas Edison was no longer in control of his own company, which was consolidated into the conglomerate General Electric and converting to an AC delivery system at that point.

In 1893, George Westinghouse won the bid to light the 1893 World's Columbian Exposition in Chicago with alternating current, beating out a General Electric bid by one million dollars. This World's Fair devoted a building to electrical exhibits. It was a key event in the history of AC power, as Westinghouse demonstrated the safety, reliability, and efficiency of a fully integrated alternating current system to the American public. At the Columbian Exposition, under a banner announcing the "Tesla Polyphase System", Tesla demonstrated a series of electrical effects previously performed throughout America and Europe,:76 included using high-voltage, high-frequency alternating current to light a wireless gas-discharge lamp.:79 An observer noted:

In 1893 Richard Dean Adams, who headed up the Niagara Falls Cataract Construction Company sought Tesla's opinion on what system would be best to transmit power generated at the falls. Over several years there had been a series of proposals and open competitions on how best to utilize power generated by the falls with many systems being proposed by several US and European companies including two-phase and three-phase AC, high-voltage DC, and even compressed air. Adams pumped Tesla for information about the current state of all the competing systems. Tesla advised Adams that a two-phased system would be the most reliable and that there was a Westinghouse system to light incandescent bulbs using two-phase alternating current. Based on Tesla's advice and Westinghouse's demonstration that they could build a complete AC system at the Columbian Exposition, a contract for building a two-phase AC generating system at the Niagara Falls was awarded to Westinghouse Electric. A further contract to build the AC distribution system was awarded to General Electric.

The mid 1890s saw the conglomerate General Electric, backed by financier J. P. Morgan, involved in takeover attempts and patent battles with Westinghouse Electric. Although a patent-sharing agreement was signed between the two companies in 1896 Westinghouse was still cash-strapped from the financial warfare. To secure further loans, Westinghouse was forced to revisit Tesla's AC patent, which bankers considered a financial strain on the company (at that point Westinghouse had paid out an estimated $200,000 in licenses and royalties to Tesla, Brown, and Peck). In 1897, Westinghouse explained his financial difficulties to Tesla in stark terms, saying that if things continue the way they were he would no longer be in control of Westinghouse Electric and Tesla would have to "deal with the bankers" to try to collect future royalties. Westinghouse convinced Tesla to release his company from the licensing agreement over Tesla's AC patents in exchange for Westinghouse Electric purchasing the patents for a lump sum payment of $216,000; this provided Westinghouse a break from what, due to alternating current's rapid gain in popularity, had turned out to be an overly generous $2.50 per AC horsepower royalty.

On 30 July 1891, at the age of 35, Tesla became a naturalized citizen of the United States, and established his South Fifth Avenue laboratory, and later another at 46 E. Houston Street, in New York. He lit electric lamps wirelessly at both locations, demonstrating the potential of wireless power transmission. In the same year, he patented the Tesla coil.



###Question: How old was tesla when he became a US citizen?

###Answer: {'answer':'35'}