Task: Question Answering
Input (English): Passage: Tchaikovsky was born in 1840 in Votkinsk, a small town in present-day Udmurtia, formerly the Imperial Russian province of Vyatka. A precocious pupil, he began piano lessons at the age of five, and could read music as adeptly as his teacher within three years. However, his parents' passion for his musical talent soon cooled. In 1850, the family decided to send Tchaikovsky to the Imperial School of Jurisprudence in Saint Petersburg. This establishment mainly served the lesser nobility or gentry, and would prepare him for a career as a civil servant. As the minimum age for acceptance was 12, Tchaikovsky was sent by his family to board at the Imperial School of Jurisprudence's preparatory school in Saint Petersburg, 800 miles (1,300 km) from his family home in Alapayevsk. Once Tchaikovsky came of age for acceptance, he was transferred to the Imperial School of Jurisprudence to begin a seven-year course of studies.Music was not a priority at the School, but Tchaikovsky regularly attended the theater and the opera with other students. He was fond of works by Rossini, Bellini, Verdi and Mozart. Piano manufacturer Franz Becker made occasional visits to the School as a token music teacher. This was the only formal music instruction Tchaikovsky received there. From 1855 the composer's father, Ilya Tchaikovsky, funded private lessons with Rudolph Kündinger, a well-known piano teacher from Nuremberg, and questioned Kündinger about a musical career for his son. Kündinger replied that nothing suggested a potential composer or even a fine performer. Tchaikovsky was told to finish his course and then try for a post in the Ministry of Justice.Tchaikovsky graduated on May 25, 1859 with the rank of titular counselor, a low rung on the civil service ladder. On June 15, he was appointed to the Ministry of Justice in Saint Petersburg. Six months later he became a junior assistant and two months after that, a senior assistant. Tchaikovsky remained there for the rest of his three-year civil service career.In 1861, Tchaikovsky attended classes in music theory organized by the Russian Musical Society and taught by Nikolai Zaremba. A year later he followed Zaremba to the Saint Petersburg Conservatory. Tchaikovsky would not give up his Ministry post "until I am quite certain that I am destined to be a musician rather than a civil servant." From 1862 to 1865 he studied harmony, counterpoint and fugue with Zaremba, while Rubinstein taught him instrumentation and composition. In 1863 he abandoned his civil service career and studied music full-time, graduating in December 1865. 
Question: What is the last name of the person Rubinstein taught instrumentation and composition?
Output (English): Tchaikovsky.