We have three identical metallic spheres A$,$ B$,$ C$.$ Initially sphere A is charged with charge $50,$ while $B$ and $C$ are neutral. First, sphere $A$ is brought into contact with sphere $B$ and then separated from it$.$ After that, sphere $A$ is brought into contact with sphere $C$ and then separated from it$.$ Finally, sphere $A$ is brought into contact with sphere B again, and then separated from it$.$ What is the final charge of sphere A