A factory wants a regenerative policy to replace its 5000 light bulbs. A light bulb lasts for 6 years. The cost of regeneration on average is $20, $16, $17, $21, $23, $19 /bulb (cost of new bulb + cost of replacing) every k- 1,2,3,4,5,6 year respectively. Use a discount factor of 0.95. Determine the optimal year to replace all the bulbs, Use value iteration.