output_description: Print the maximum number of coins you can get.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      A B
attempt: N, K = map(int, input().split())
  S = input()
  if S[0] == "0":
      divide = []
  else:
      divide = [0]
  tmp = 1
  for i in range(1, N):
      if S[i] == S[i - 1]:
          tmp += 1
      else:
          divide += [tmp]
          tmp = 1
  divide += [tmp]
  le = len(divide)
  zero = [0] * 2 * le + divide + [0] * 2 * le
  su = [0]
  for i in range(0, 5 * le):
      su += [su[-1] + zero[i]]
  del su[0]
  lle = len(su)
  mxm = 0
  for k in range(K, lle):
      if 2 * k + 1 >= lle:
          break
      cd = su[2 * k + 1] - su[2 * k - 2 * K]
      if cd > mxm:
          mxm = cd
  print(mxm)
  
problem_description: Statement
  
  There are two buttons, one of size A and one of size B.
  
  When you press a button of size X, you get X coins and the size of that button
  decreases by 1.
  
  You will press a button twice. Here, you can press the same button twice, or
  press both buttons once.
  
  At most how many coins can you get?
samples: [{"input": "5 3", "output": "9\n    \n\nYou can get 5 + 4 = 9 coins by pressing the button of size 5 twice, and this\nis the maximum result.\n\n* * *"}, {"input": "3 4", "output": "7\n    \n\n* * *"}, {"input": "6 6", "output": "12"}]