context: Gorbachev, Mikhail Sergeevich (May 25, 1989 — March 15, 1990) Lukyanov, Anatoly Ivanovich (March 15, 1990 - September 4, 1991) is vacant (September 4 - December 26, 1991)
question: Who was the last chairman of the Supreme Council of the USSR?
answers.text: Lukyanov, Anatoly Ivanovich