There is an introduction using piano and electric piano, with Paul McCartney and George Martin playing two different piano parts on separate ends of the same Steinway grand piano. The Steinway appears only in the song's intro and was overdubbed separately, as was McCartney's bass. The electric piano is a HohnerPianet, and you can hear the instrument's tremolo being switched off after the intro.
Credits
John Lennon — electric piano, acoustic rythm guitar