Charge Redistribution Between Conducting Spheres

Two isolated conducting spheres have radii of $r_1 = 5\ \text{cm}$ and $r_2 = 10\ \text{cm}$ and initial charges of $Q_1 = 3\ \text{nC}$ and $Q_2 = -1\ \text{nC}$, respectively. The spheres are connected by a thin conducting wire and then separated. What is the final charge on the smaller sphere?