Mohamed Yousef is a tall, handsome practitioner of kung fu. In fact, he's an Egyptian champion who recently won an international competition.
But a month ago, when he collected his gold medal at the championship in Russia, he posed for a picture after putting on a yellow T-shirt with a hand holding up four fingers.
That's the symbol of Rabaa al-Adawiya, the Cairo square where Egyptian security forces opened fire in August on supporters of ousted Islamist President Mohammed Morsi. Hundreds were killed, including seven of Yousef's friends.