You have 36 rocks.each of them contains a certain amount of uranium.You have been assigned the task to find the top 3 rocks with the highest amount of uranium and also to discard the one with the least amount in it. You have a machine that can arrange the rocks in decreasing order of their radiation.But it can do it for only 6 rocks at most in one cycle.Every cycle of machine costs 10 units. What is the minimum amount of units in which you can achieve the result?