Two blocks $A$ and $B$ of masses $m_A=1 \mathrm{~kg}$ and $\mathrm{m}_{\mathrm{B}}=3 \mathrm{~kg}$ are kept on the table as shown in figure. The coefficient of friction between $A$ and $B$ is 0.2 and between $B$ and the surface of the table is also 0.2 . The maximum force $F$ that can be applied on B horizontally, so that the block A does not slide over the block B is: [Take $\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^2$ ]