The composition of an air-entrained concrete is given below:
$\begin{array}{lcr} \text{Water} & : & 184 \: kg/m^3 \\ \text{Ordinary Portland Cement (OPC)} & : & 368 \: kg/m^3 \\ \text{Sand} & : & 606 \: kg/m^3 \\ \text{Coarse aggregate} & : & 1155 \: kg/m^3 \end{array}$
Assume the specific gravity of OPC, sand and coarse aggregate to be $3.14$, $2.67$, and $2.74$, respectively. The air content is ______ $liters/m^3$.