$ABC.$ Initially the charge of the sphere at point $A$ is $q_{A}=0$ and the spheres at $B$ and $C$ carry the same charge $q_{B}=q_{C}=q.$ It is known that the sphere $B$ exerts an electrostatic force on $C$ which has a magnitude $F=4~\mbox{N}.$ Suppose an engineer connects a very thin conducting wire between spheres $A$ and $B.$ Then she removes the wire and connects it between spheres $A$ and $C.$ After these operations, what is the magnitude of the force of interaction **in Newtons** between $B$ and $C?$