A flea jumps by exerting a force of 1.39 x 10-5 N straight down on the ground. A breeze blowing on the flea parallel to the ground exerts a force of 0.459 x 10-6 N on the flea. Find the magnitude of the acceleration of the flea if its mass is 6.3 x 10-7 kg. Do not neglect the force of gravity and give your answer in microns per square seconds.