You enter a walked orchard to pick some mangoes. you picked a few and started to look for the exit. there are three wall each of which has a gate, and at each gate there is a guard. as approach the first gate, the first gate, the guard asks you to give him half the mangoes and then three more. he sends you off, so you approach the second gate and this guard, too, asks you for half of your mangoes and then three more. you move on to the third gate and, once again, the guard asks for half the fruit and three more. he then allows you to exit. you look down in your basket and, sadly, you only have one mangoes left. how many mangoes did you pick up before paying the outrageous tax?