The students enter the building through a side door, where they promptly submit backpacks and any other personal items to the N.Y.P.D. safety agent who greets them at the steps. There’s a male agent for the boys, a female for the girls. Everyone is scanned for weapons, cellphones, and drugs upon entering the building. Some of the more committed students have already hidden items inside a shoe, their underwear, perhaps the lining of a wig. The rest have scattered belongings in various spots throughout the neighborhood.