A block of ice of mass $1.0\ \text{kg}$, at $-40\ ^\circ\text{C}$, is dropped into $0.50\ \text{kg}$ of water at $10\ ^\circ\text{C}$ in an insulated vessel of negligible heat capacity. The specific heats are $2100\ \text{J/(kg K)}$ for ice and $4200\ \text{J/(kg K)}$ for water, and the latent heat of fusion is $3.36 \times 10^5\ \text{J/kg}$. When everything has settled, how much ice is there?