Help understanding Bronze problem Stuck in a rut

Problem: USACO

I didn’t understand the sample test case. According to the question, my thought is all cow can eat infinity cells of grass, because no two cells are eaten by a cow.

For many cows, they run into a square that has already been eaten by another cow, so they stop moving.

But in the sample case, how it happened?
I see 3 cows has North direction and 3 others has East direction and no one will stop.

The E cows are the red ones, while the N cows are the blue ones. It should be clear how some cows will run into the paths left by other cows.