Try counting the tops of the flagpoles. There are two on the left, might be three even, that are almost overlapping. Plus "flanking Trump" is a little hard to define with this viewpoint. I think there might even be more if we could pan out, because it looks like the start of another bunch on the right.
I'm unsure if that's an 18th one just out of frame or a person wearing something red.
Try counting the tops of the flagpoles. There are two on the left, might be three even, that are almost overlapping. Plus "flanking Trump" is a little hard to define with this viewpoint. I think there might even be more if we could pan out, because it looks like the start of another bunch on the right.