TOPSHOTS Supporters of the Muslim Brotherhood chant slogans and raise four fingers, the symbol known as "Rabaa", which means four in Arabic, remembering those killed in the crackdown on the Rabaa al-Adawiya protest camp in Cairo last year, during a demonstration in Cairo on January 24, 2014. A suicide bomber struck Cairo police headquarters on Friday, the first of three bombings in the Egyptian capital that killed five people ahead of the anniversary of the 2011 uprising. AFP PHOTO/MAHMOUD KHALED