Two spherical conductor $B$ and $C$ having equal radii and carrying equal charges in them repel each other with a force $F$ when kept apart at some distance. A third spherical conductor having same radius as that of $B$ but uncharged brought in contact with $B$, then brought in contact with $\mathrm{C}$ and finally removed away from both. The new force of repulsion, between $B$ and $C$ is