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 = int(input())
  B = list(map(int, input().split()))
  cnt = B[0] + B[N - 2]
  for i in range(1, N - 1):
      cnt += min(B[i - 1], B[i])
  print(cnt)
  
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"}]