A $5$ kg block $($B$)$ is placed on top of an $8$ kg block $($A$),$ and both blocks are resting on a horizontal table. There is no friction between block A and the table. The coefficient of friction between blocks A and B is $0\mathrm{.}75.$ A light string is attached to block A$,$ passes over a frictionless and massless pulley, and has block C hanging on the other end.When released from rest, what is the maximum mass of block C that allows blocks A and B to move together without slipping?