A town (green=3 border) is infested with rats (grey=5 scattered inside). The Pied Piper (magenta=6) enters from the left. In the masked grid, the piper has moved to the town exit on the right, and all the rats have followed — forming a line trailing behind the piper toward the right edge. The town interior is now clear of rats. Later, when the town refuses payment, the piper leads children (blue=4) away instead.