How many bricks would i need to make a wall big enough to hold back the chinese?

the great wall of china was designed to keep people OUT

and it turns out there are a few holes along the way



i am quite scared of the idea of the chinese taking over the world so roughly how many bricks will i need to build a very big wall or a medium sized castle
1. crazy.

2. a wall 30 feet high, 15 feet thick, with a 50x50 opening (for your