A piston-cylinder device equipped with a resistance heater is initially filled with 0.4 kg of saturated water vapor at 200 degrees C. Now the heater is turned on, the steam is compressed, and there is heat loss to the surrounding air. At the end of the process, the temperature and pressure of steam in the container are measured to be 300 degrees C and 0.5 MPa. The net energy transfer to the steam during this process is