Problem Statement 
 You are a playing a card game consisting of 1 or more rounds in which you may purchase 1 or more cards during each round. The cost of buying c cards in round r is k^r * c^2 (in the first round, r = 0). For example, if k = 2, and you buy 4 cards in the first round, 1 card in the second round, and 1 card in the third round, it would cost:
 2^0 * 4^2 = 16 for the first four cards,
 2^1 * 1^2 = 2 for the fifth card,
 2^2 * 1^2 = 4 for the last card.
The six cards cost you 22. There is a cheaper way to buy 6 cards: buy 3, then 2, then 1 for a cost of 9+8+4 = 21. Suppose you wish to buy n cards given some round multipler k. Return the minimum cost of purchasing the cards.


Definition 
 Class:  CardCosts  Method:  mincost  Parameters:  int, int  Returns:  long  Method signature:  long mincost(int n, int k)  (be sure your method is public) 




Notes 
  Watch for overflow errors; a 32bit dataype is not sufficient for this problem. 

Constraints 
  n is between 0 and 1000000 inclusive. 
  k is between 1 and 1000 inclusive. 

Examples 
0)  
  Returns: 21  This is the example from the problem definitiion. The best solution is to purchase 3 cards at 9, then 2 cards at 8, then 1 card at 4. 


1)  
  Returns: 160000  k is too large to be worthwhile. Purchase all cards on the first round. 


2)  
 
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6)  
 