The drawing shows a particle carrying a positive charge q at the coordinate origin, as well as a target located in the third quadrant. A uniform magnetic field is directed perpendicularly into the plane of the paper. The charge can be projected in the plane of the paper only, along the positive or negative x or y axis. There are four possible directions ( x, -x, y, -y) for the initial velocity of the particle. The particle can be made to hit the target for only two of the four directions. Which two directions are they