The heat extracted out of x gram of water initially at $50^{\circ} \mathrm{C}$ to cool it down to $0^{\circ} \mathrm{C}$ is sufficient to evaporate ( $1000-x$ ) gram of water also initially at $50^{\circ} \mathrm{C}$. The value of $x$ (closest integer) is $\_\_\_\_$ . (Take latent heat of water $2256 \mathrm{~kJ} / \mathrm{kg} . \mathrm{K}$, specific heat capacity of water $4200 \mathrm{~J} / \mathrm{kg} . \mathrm{K}$ )