output_description: Print the maximum possible number of consecutive people standing on hands
  after at most K directions.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N K
      S
attempt: n,k=list(map(int,input().split()))
  t=input()
  z=[]
  p=t[0]
  if t[0]=="0":
    z.append(0)
  z.append(0)
  for i in t:
    if i == p:
      z[-1]+=1
    eln,k=list(map(int,input().split()))
  t=input()
  z=[]
  p=t[0]
  if t[0]=="0":
    z.append(0)
  z.append(0)
  for i in t:
    if i == p:
      z[-1]+=1
    else:
      p=i
      z.append(1)
  if k*2+1 >= len(z):
    r=n
  else:
    p=sum(z[:2*k+1])
    r=p
    for i in range(0,len(z)-2*k-2,2):
      e=z[i]+z[i+1]
      p-=e
      f=z[2*k+i+1]+z[2*k+i+2]
      p+=f
      r=max(r,p)
  print(r)se:
      p=i
      z.append(1)
  if k*2+1 >= len(z):
    r=n
  else:
    p=sum(z[:2*k+1])
    r=p
    for i in range(0,len(z)-2*k-2,2):
      e=z[i]+z[i+1]
      p-=e
      f=z[2*k+i+1]+z[2*k+i+2]
      p+=f
      r=max(r,p)
  print(r)
problem_description: Statement
  
  N people are arranged in a row from left to right.
  
  You are given a string S of length N consisting of `0` and `1`, and a positive
  integer K.
  
  The i-th person from the left is standing on feet if the i-th character of S
  is `0`, and standing on hands if that character is `1`.
  
  You will give the following direction at most K times (possibly zero):
  
  **Direction** : Choose integers l and r satisfying 1 \leq l \leq r \leq N, and
  flip the l-th, (l+1)-th, ..., and r-th persons. That is, for each i = l, l+1,
  ..., r, the i-th person from the left now stands on hands if he/she was
  standing on feet, and stands on feet if he/she was standing on hands.
  
  Find the maximum possible number of **consecutive** people standing on hands
  after at most K directions.
samples: [{"input": "5 1\n    00010", "output": "4\n    \n\nWe can have four consecutive people standing on hands, which is the maximum\nresult, by giving the following direction:\n\n  * Give the direction with l = 1, r = 3, which flips the first, second and third persons from the left.\n\n* * *"}, {"input": "14 2\n    11101010110011", "output": "8\n    \n\n* * *"}, {"input": "1 1\n    1", "output": "1\n    \n\nNo directions are necessary."}]