output_description: Print the maximum satisfaction that you can obtain.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N K
      t_1 d_1
      t_2 d_2
      .
      .
      .
      t_N d_N
attempt: n,k=map(int,input().split())
  td=sorted([list(map(int,input().split())) for i in range(n)],reverse=True,key=lambda x:x[1])
  #print(td)
  ans=0
  kinds=dict()
  for i in range(k):
      ans+=td[i][1]
      if td[i][0] in kinds:
          kinds[td[i][0]].append(td[i][1])
      else:
          kinds[td[i][0]]=[td[i][1]]
  ans+=(len(kinds)**2)
  #kindsの中はソートされている状況
  #print(kinds)
  ans_=[ans]
  for i in range(k,n):
      if td[i][0] not in kinds:
          mi=[1000000000,1000000000]
          for j in kinds:
              if len(kinds[j])>1:
                  if mi[1]>kinds[j][-1]:
                      mi=[j,kinds[j][-1]]
          if mi=[1000000000,1000000000]:
              break
          else:
              ans=ans-len(kinds)**2+(len(kinds)+1)**2-mi[1]+td[i][1]
              kinds[mi[0]].pop(-1)
              kinds[td[i][0]]=[td[i][1]]
              ans_.append(ans)
  #print(kinds)
  print(max(ans_))
problem_description: Statement
  
  There are N pieces of sushi. Each piece has two parameters: "kind of topping"
  t_i and "deliciousness" d_i. You are choosing K among these N pieces to eat.
  Your "satisfaction" here will be calculated as follows:
  
    * The satisfaction is the sum of the "base total deliciousness" and the "variety bonus".
    * The base total deliciousness is the sum of the deliciousness of the pieces you eat.
    * The variety bonus is x*x, where x is the number of different kinds of toppings of the pieces you eat.
  
  You want to have as much satisfaction as possible. Find this maximum
  satisfaction.
samples: [{"input": "5 3\n    1 9\n    1 7\n    2 6\n    2 5\n    3 1", "output": "26\n    \n\nIf you eat Sushi 1,2 and 3:\n\n  * The base total deliciousness is 9+7+6=22.\n  * The variety bonus is 2*2=4.\n\nThus, your satisfaction will be 26, which is optimal.\n\n* * *"}, {"input": "7 4\n    1 1\n    2 1\n    3 1\n    4 6\n    4 5\n    4 5\n    4 5", "output": "25\n    \n\nIt is optimal to eat Sushi 1,2,3 and 4.\n\n* * *"}, {"input": "6 5\n    5 1000000000\n    2 990000000\n    3 980000000\n    6 970000000\n    6 960000000\n    4 950000000", "output": "4900000016\n    \n\nNote that the output may not fit into a 32-bit integer type."}]