The electric field in a region is given by $\vec{E}=\frac{2}{5} E_0 \hat{i}+\frac{3}{5} E_0 \hat{j}$ with $E_0=4.0 \times 10^3 \frac{N}{C}$. The flux this field through a rectangular surface area $0.4 \mathrm{~m}^2$ parallel to the $\mathrm{Y}-\mathrm{Z}$ plane is $\_\_\_\_$ $\mathrm{Nm}^2 \mathrm{C}^{-1}$.