A gas is enclosed in a cylinder with a movable frictionless piston. Its initial thermodynamic state at pressure $P_{i}=10^{5} \mathrm{~Pa}$ and volume $V_{i}=10^{-3} \mathrm{~m}^{3}$ changes to a final state at $P_{f}=(1 / 32) \times 10^{5} \mathrm{~Pa}$ and $V_{f}=8 \times 10^{-3} \mathrm{~m}^{3}$ in an adiabatic quasi-static process, such that $P^{3} V^{5}=$ constant. Consider another thermodynamic process that brings the system from the same initial state to the same final state in two steps: an isobaric expansion at $P_{i}$ followed by an isochoric (isovolumetric) process at volume $V_{f}$. The amount of heat supplied to the system in the two-step process is approximately