$100$ TAs are arranged in a $10\backslash$times $10$ square grid for the Lunar New Year square dance. TA $1$

can see TA $2$ if the straight line drawn between TA $1$ and $2$ passes through no other people.

For example, a TA standing at $(0,0)$ can see a TA standing at $(2,1),$ but they cannot see a TA

standing at $(2,0),$ since the TA at $(1,0)$ is blocking their line of sight. Prove that there are no

five TAs who can all see each other.