Air is held inside a non-insulated cylinder using a piston (mass M=25 kg and area A=100 cm²) and stoppers (of negligible area), as shown in the figure. The initial pressure  and temperature  of air inside the cylinder are 200 kPa and 400^oC, respectively. The ambient pressure  and temperature  are 100 kPa and 27^oC, respectively. The temperature of the air inside the cylinder (^oC) at which the piston will begin to move is __________ (correct to two decimal places).