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 = input()
  comp = []
  
  bef = s[0]
  temp = 0
  
  # if s[0] != "L":
  #     comp.append(0)
  #
  # if s[-1] != "L":
  #     comp.append(0)
  
  for c in s:
      if c == bef:
          temp += 1
      else:
          comp.append(temp)
          temp = 1
          bef = c
  comp.append(temp)
  # print(comp)
  #
  # n = len(comp)
  #
  # leng = k*2 +1
  #
  # if leng >= n:
  #     print("over")
  #     print(sum(comp))
  # else:
  #     step = (n-leng)//2
  #     now = 0
  #     ans = 0
  #     for i in range(leng):
  #         now += comp[i]
  #     ans = now
  #     print(ans)
  #     for i in range(step):
  #         now -= (comp[i*2]+comp[i*2+1])
  #         now += (comp[i*2+2]+comp[i*2+3])
  #         if now > ans:
  #             ans = now
  #         print(ans)
  #
  #     print(ans)
  
  init = 0
  n = len(comp)
  for c in comp:
      init += c - 1
  
  inside = 0
  if n % 2 == 0:
      inside = n // 2 - 1
  else:
      inside = n // 2
  
  outside = 0
  
  if n % 2 == 0:
      outside = n // 2 - 1
  else:
      outside = 0
  
  tot = inside + outside
  
  if k >= tot:
      print(sum(comp) - 1)
  elif k > inside:
      print(init + 2 * inside + outside)
  else:
      print(init + 2 * k)
  
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"}]