How can you heat $\displaystyle 1 \,\mathrm{kg}$ mineral water which is at a temperature of $\displaystyle 0 \,{}^\circ \mathrm{C}$ to at least $\displaystyle 60 \,{}^\circ \mathrm{C}$ with using $\displaystyle 1 \,\mathrm{kg}$ water at a temperature of $\displaystyle 100 \,{}^\circ \mathrm{C}$?