Field due to the positive charge in the direction away from the origin and Field due to negative charge is in the direction of the origin.
The charge is approaching towards origin and has only enough speed to cross the origin after which it should stop.
Work needs to be done to move charge inside the field
But it gets attracted due to negative charge because of which it gains energy to move across the origin.
Therefore there will be potential energy gained by the charge which should be positive or more than zero