If you use a monospaced font (all characters same width), it will be easier to read and write. You can get that in the AGF by using the "#" button, which puts \[CODE] tags around your input, e.g.:
Code:
x x 5 x 0 x
3 x x x 0 x
x 0 x x 1 x
x 1 x x 2 x
Or choose one of the monospaced fonts in the Fonts dropdown, like Courier New, Fixedys, or Lucida Console:
x x 5 x 0 x
3 x x x 0 x
x 0 x x 1 x
x 1 x x 2 x