If $$A = \displaystyle\left[\begin{array}{cccc} -6 &5 &9 &1 \cr -5 &4 &-2 &2 \cr -2 &4 &5 &1 \cr -6 &1 &-5 &0 \cr \end{array}\right]$$ $$B = \displaystyle\left[\begin{array}{cccc} 7 &-2 &4 &4 \cr 1 &2 &7 &-2 \cr -7 &-8 &8 &5 \cr 7 &8 &-6 &-7 \cr -4 &-6 &-4 &3 \cr 9 &1 &5 &-2 \cr -2 &4 &-9 &-8 \cr \end{array}\right]$$
then the size of $AB$ is
and the size of $BA$ is .

NOTE: If either of the products is not defined, type UNDEFINED for you answer.