I want to know the answer to the following question:
How many people marched on January 11 against terrorism?
All the background I'm provided with is that "On 7 January 2015, two French Muslim extremists attacked the Paris headquarters of Charlie Hebdo and killed thirteen people, and on 9 January, a third terrorist killed four hostages during an attack at a Jewish grocery store at Porte de Vincennes.". Is that enough to answer the question?