In the arrangement shown in the figure mass of the block `B` and `A` are `2m` , `8m` respetively. Surface between `B` floor is smooth. The block `B` is connected to block `C` by means of a pulley. If the whole system is released then the minimum value of mass of the block `C` so that the block `A` remains stationary with respect to `B` is: (Coefficient of friction between `A` and `B` is mu and pulley is ideal).