Two blocks of masses $M=3 \mathrm{kg}$ and $m=2 \mathrm{kg}$, are in contact on a horizontal table. A constant horizontal force $F=5 \mathrm{N}$ is applied to block $M$ as shown. There is a constant frictional force of $2 \mathrm{N}$ between the table and the block $m$ but no frictional force between the table and the first block $M$, then the acceleration of the two blocks is