Q:Given the following context:  In writing Young Modern, Johns tried to make the music sound very simple, despite a complex musical structure. The lyrics were written after the music was created, sometimes as late as the day of recording. As Johns dreads writing lyrics, he suggested that the band could produce an instrumental album at some stage in the future. Johns is the band's primary songwriter, and notes that while Joannou and Gillies do not have significant influence on what he writes, they are key to the band's overall sound. For that album, Hamilton co-wrote four songs with Johns including the APRA Award-winning "Straight Lines". Joannou believed that Young Modern was simpler than Diorama but "still as complex underneath with simple pop song elements". He said that much of the band's success resulted from trying to push themselves harder in recording and writing. Self-producing has allowed the band to do so without the pressures of a record label.Gillies notes that Silverchair will often "run the risk of losing fans" with their work, and this was evident in the changes in musical direction in Diorama and Young Modern. However, he described this as a good thing, describing the fact "that we haven't been pigeonholed, and people really don't know what to expect" as one of the attractive elements of the band. Despite the ups and downs of success at a young age, Gillies says the band "appreciate what we've achieved and what we've got" in their careers. The band have received six APRA Awards with Johns winning three songwriting awards at the 2008 ceremony.  answer the following question:  What are the names of the people who are key to the band's overall sound?
A:
Gillies