Ideal Gas Law Questions

If $10^{-4}{\text{dm}}^3$ of water is introduced into a $1.0{\text{dm}}^3$ flask to $300\text{K}$, how many moles of water are in the vapour phase when equilibrium is established?(Given: Vapour pressure of ${\text{H}}_2\text{O}$ at $300\text{K}$ is $3170\text{Pa}$; $R=8.314{\text{J K}}^{-1}{\text{mol}}^{-1}$)