Russian dissident punk rock collective Pussy Riot and feminist group Femen staged a protest that lasted about 15 minutes outside the Russian Pavilion at the Venice Biennale on Wednesday.     The Pussy Riot members wore pink balaclavas and the Femen protesters were topless, as usual.     Yellow and blue flares were lit, Ukrainian flags were waved, and anti-Russian banners were displayed.     ALL RIGHTS RESERVED © Copyright ANSA