Difference

Consider the following two events #A# and #B#:
\[\begin{array}{rcl}
A &=& \{1,\,2,\,5,\,9,\,11,\,12\}\\
B &=&\{1,\,4,\,5,\,11,\,18,\,19\}
\end{array}\]

What is the difference of #A# and #B#?

Note: Enter the elements in order from smallest to largest.

#A \,\backslash\, B = \{#, , #\}#