Read the following paragraph and extract the answer for the question: What is the first name of the person who announced his departure to the rest of the group on 20 September?

New strains developed between the band members regarding the appointment of a financial adviser, the need for which had become evident without Epstein to manage business affairs. Lennon, Harrison and Starr favoured Allen Klein, who had managed the Rolling Stones and Sam Cooke; McCartney wanted Lee and John Eastman – father and brother, respectively, of Linda Eastman, whom McCartney married on 12 March. Agreement could not be reached, so both Klein and the Eastmans were temporarily appointed: Klein as the Beatles' business manager and the Eastmans as their lawyers. Further conflict ensued, however, and financial opportunities were lost. On 8 May, Klein was named sole manager of the band, the Eastmans having previously been dismissed as the Beatles' lawyers. McCartney refused to sign the management contract with Klein, but he was out-voted by the other Beatles.Martin stated that he was surprised when McCartney asked him to produce another album, as the Get Back sessions had been "a miserable experience" and he had "thought it was the end of the road for all of us". The primary recording sessions for Abbey Road began on 2 July 1969. Lennon, who rejected Martin's proposed format of a "continuously moving piece of music", wanted his and McCartney's songs to occupy separate sides of the album. The eventual format, with individually composed songs on the first side and the second consisting largely of a medley, was McCartney's suggested compromise. On 4 July, the first solo single by a Beatle was released: Lennon's "Give Peace a Chance", credited to the Plastic Ono Band. The completion and mixing of "I Want You (She's So Heavy)" on 20 August 1969 was the last occasion on which all four Beatles were together in the same studio. Lennon announced his departure to the rest of the group on 20 September, but agreed to withhold a public announcement to avoid undermining sales of the forthcoming album.Released six days after Lennon's declaration, Abbey Road sold 4 million copies within three months and topped the UK charts...
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