How much work is required, using an ideal Carnot refrigerator, to change 0.500 kg of tap water

Question:

How much work is required, using an ideal Carnot refrigerator, to change 0.500 kg of tap water at 10.0°C into ice at - 20.0°C? Assume the temperature of the freezer compartment is held at -20.0°C and the refrigerator exhausts energy into a room at 20.0°C.