Task: Question Answering
Input (English): Passage: ABKCO Industries was formed in 1968 by Allen Klein as an umbrella company to ABKCO Records. Klein hired May Pang as a receptionist in 1969. Through involvement in a project with ABKCO, Lennon and Ono met her the following year. She became their personal assistant. In 1973, after she had been working with the couple for three years, Ono confided that she and Lennon were becoming estranged. She went on to suggest that Pang should begin a physical relationship with Lennon, telling her, "He likes you a lot." Astounded by Ono's proposition, Pang nevertheless agreed to become Lennon's companion. The pair soon left for Los Angeles, beginning an 18-month period he later called his "lost weekend". In Los Angeles, Pang encouraged Lennon to develop regular contact with Julian, whom he had not seen for two years. He also rekindled friendships with Starr, McCartney, Beatles roadie Mal Evans, and Harry Nilsson. While Lennon was drinking with Nilsson, he misunderstood something that Pang had said and attempted to strangle her. Lennon relented only after he was physically restrained by Nilsson.In June, Lennon and Pang returned to Manhattan in their newly rented penthouse apartment where they prepared a spare room for Julian when he visited them.  Lennon, who had been inhibited by Ono in this regard, began to reestablish contact with other relatives and friends.  By December, he and Pang were considering a house purchase, and he refused to accept Ono's telephone calls. In January 1975, he agreed to meet Ono, who claimed to have found a cure for smoking. After the meeting, he failed to return home or call Pang. When Pang telephoned the next day, Ono told her that Lennon was unavailable because he was exhausted after a hypnotherapy session. Two days later, Lennon reappeared at a joint dental appointment; he was stupefied and confused to such an extent that Pang believed he had been brainwashed. Lennon told Pang that his separation from Ono was now over, although Ono would allow him to continue seeing her as his mistress. 
Question: What is the last name of the person who called an 18-month period in Los Angeles his "lost weekend?"?
Output (English): Lennon.