There is a vertical pole of 30 feet high. A snail climbs up this pole. It climbs eight feet , but instantly slides down by five feet , thus gaining only three feet up . This process repeats till it reaches the top of the pole , on reaching which it won't slide down. If the snail takes two minutes to climb one foot , and no time to slide down , find the time taken by the snail to reach the top of the pole.