A police officer fires pepper spray at a protester wearing a Guy Fawkes mask on the back of his head during a demonstration in Salvador June 20, 2013. Protesters are expected to flood more than 100 Brazilian cities and surround two international football matches later on Thursday, as lower transport fares and promises of better public services fail to stem the tide of discontent in Latin America's biggest country. REUTERS/Jorge Silva (BRAZIL - Tags: SPORT SOCCER CIVIL UNREST POLITICS CRIME LAW)