US singer-songwriter Katy Perry performs on stage during the 17th Life Ball in Vienna on May 16, 2009. Life Ball is Europe's largest annual AIDS charity and the organisers this year hope to raise more than one million euros (about 1.6 million USD) to help people living with HIV.AFP PHOTO/JOE KLAMAR (Photo credit should read JOE KLAMAR/AFP/Getty Images)
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