An electric dipole is placed on x-axis in proximity to a line charge of linear charge density 3.0 $\times 10-$6 C/m. Line charge is placed on z-axis and positive and negative charge of dipole is at a distance of 10 mm and 12 mm from the origin respectively. If total force of 4N is exerted on the dipole, find out the amount of positive or negative charge of the dipole.