Maggie graphs the six possible lines of the form $y=m x+b$ where $m$ is either 1 or -2 , and $b$ is either 0,1 or 2 . For example, one of the lines is $y=x+2$. The lines are all graphed on the same axes. There are exactly $n$ distinct points, each of which lies on two or more of these lines. What is the value of $n$ ?