Nine people are sitting in the squares of a 3 by 3 grid, one in each square, as shown. Two people are called *neighbours* if they are sitting in squares that share a side. (People in diagonally adjacent squares, which only have a point in common, are not called neighbours.) [IMAGE_PLACEHOLDER] Each of the nine people in the grid is either a truth-teller who always tells the truth, or a liar who always lies.

Every person in the grid says: 'My neighbours are all liars'.

Given only this information, what are the smallest number and the largest number of people who could be telling the truth?