output_description: Print the maximum possible number of happy people after at most K operations.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N K
      S
attempt: N, K = map(int, input().split())
  S = str(input())
  
  
  def happy_now(s):
      number1 = 0
      number2 = 0
      number3 = 0
      if s[0] == "L":
          number1 += 1
          number2 += 1
      if s[len(s) - 1] == "R":
          number1 += 1
          number2 += 1
      for i in range(len(s) - 1):
          if s[i] == "R" and s[i + 1] == "L":
              number1 += 2
              number3 += 1
      return [len(s) - number1, number2, number3]
  
  
  happy_people = happy_now(S)[0]
  unhappy_edge_place = happy_now(S)[1]
  unhappy_not_edge_place = happy_now(S)[2]
  
  # print(happy_people,unhappy_edge_place,unhappy_not_edge_place)
  
  ans = 0
  
  if unhappy_not_edge_place - 1 >= K:
      ans = happy_people + 2 * K
  
  else:
      ans = happy_people + 2 * max(unhappy_not_edge_place - 1, 0)
      if K - (unhappy_not_edge_place - 1) >= 3:
          ans += 1 + unhappy_edge_place
      elif K - (unhappy_not_edge_place - 1) == 2:
          ans += min(1 + unhappy_edge_place, 2)
      elif K - (unhappy_not_edge_place) == 1:
          ans += min(1 + unhappy_edge_place, 1)
  
  print(min(ans, len(S) - 1))
  
problem_description: Statement
  
  There are N people standing in a queue from west to east.
  
  Given is a string S of length N representing the directions of the people. The
  i-th person from the west is facing west if the i-th character of S is `L`,
  and east if that character of S is `R`.
  
  A person is happy if the person in front of him/her is facing the same
  direction. If no person is standing in front of a person, however, he/she is
  not happy.
  
  You can perform the following operation any number of times between 0 and K
  (inclusive):
  
  Operation: Choose integers l and r such that 1 \leq l \leq r \leq N, and
  rotate by 180 degrees the part of the queue: the l-th, (l+1)-th, ..., r-th
  persons. That is, for each i = 0, 1, ..., r-l, the (l + i)-th person from the
  west will stand the (r - i)-th from the west after the operation, facing east
  if he/she is facing west now, and vice versa.
  
  What is the maximum possible number of happy people you can have?
samples: [{"input": "6 1\n    LRLRRL", "output": "3\n    \n\nIf we choose (l, r) = (2, 5), we have `LLLRLL`, where the 2-nd, 3-rd, and 6-th\npersons from the west are happy.\n\n* * *"}, {"input": "13 3\n    LRRLRLRRLRLLR", "output": "9\n    \n\n* * *"}, {"input": "10 1\n    LLLLLRRRRR", "output": "9\n    \n\n* * *"}, {"input": "9 2\n    RRRLRLRLL", "output": "7"}]