An air standard Otto cycle has thermal efficiency of $0.5$ and the mean effective pressure of the cycle is $1000 \: kPa$. For air, assume specific heat ratio $\gamma=1.4$ and specific gas constant $R=0.287 \: kJ/kg \cdot K$. If the pressure and temperature at the beginning of the compression stroke are $100 \: kPa$ and $300 \: K$, respectively, then the specific net work output of the cycle is _____ $kJ/kg$ (round off to two decimal places).