Complex sentence: In 1978 the band performed at the last BOOM festival in Novi Sad and in 1979 at Zaječar Gitarijada where they were considered to be victorious, but were the only band from Belgrade which the audience did not like.
Split into simpler sentences: In 1978 the band performed at the last BOOM festival in Novi Sad and in 1979 at Zaječar Guitar festival where they were considered to be victorious. They were the only band from Belgrade which the audience did not like.