Brazilian students shout anti-government slogans and throw water on police in front of the National Congress during a protest against corruption in Brasilia August 17, 2005. Thousands of left-wing militants demanded that President Luiz Inacio Lula da Silva step down on Wednesday as new allegations of tax evasion by his ruling party added fuel to a graft scandal. Demonstrators marched through the capital in the first mass protest against Lula since allegations surfaced 11 weeks ago that the ruling Worker's Party bribed lawmakers to support legislation. REUTERS/Sergio Moraes SM/PEK/mk