2 kg of ice at -10°C is heated until it becomes all water vapor. If it is known that the specific heat of water is 1 kcal/kg°C, the specific heat of ice is 0.5 kcal/kg°C, the heat of melting of ice is 80 kcal/kg, and the heat of water vapor is 540 kcal/kg, calculate the heat required to vaporize all of the ice. !​