Buggy python submission (verdict: Runtime Error):
n, k = map(int, input().split())
s = input()

on = []
off = []

acnt = 0
bcnt = 0
for i in s:
  if i == '0':
    if bcnt > 0:
      off.append(bcnt)
      bcnt = 0
    acnt += 1
  else:
    if acnt > 0:
      on.append(acnt)
      acnt = 0
    bcnt += 1
if bcnt > 0:
  off.append(bcnt)
  bcnt = 0
if acnt > 0:
  on.append(acnt)
  acnt = 0
ans = 0
if s[0] == '1':
  for i in range(len(on)-k+1):
    s = 0
    if i == 0:
      a = sum(on[i:i+k])
      b = sum(off[i:i+k+1])
    else:
      a += on[i+k-1]
      a -= on[i-1]
      if i+k <= len(off)-1:
        b += off[i+k]
      b -= off[i-1]
    # print (a,b)
    s = a+b
    ans = max(ans,s)
else:
  for i in range(len(on)-k+1):
    if i == 0:
      a = sum(on[i:i+k])
      b = sum(off[i:i+k])
    elif i == 1:
      a = sum(on[i:i+k])
      b = sum(off[i-1:i+k])
    else:
      a += on[i+k-1]
      a -= on[i-1]
      b += off[i+k-1]
      b -= off[i-1]
    s = a+b
    ans = max(ans,s)
if ans == 0:
  print (n)
else:
  print (ans)


Fixed submission:
n, k = map(int, input().split())
s = input()

on = []
off = []

acnt = 0
bcnt = 0
for i in s:
  if i == '0':
    if bcnt > 0:
      off.append(bcnt)
      bcnt = 0
    acnt += 1
  else:
    if acnt > 0:
      on.append(acnt)
      acnt = 0
    bcnt += 1
if bcnt > 0:
  off.append(bcnt)
  bcnt = 0
if acnt > 0:
  on.append(acnt)
  acnt = 0
ans = 0
if s[0] == '1':
  for i in range(len(on)-k+1):
    s = 0
    if i == 0:
      a = sum(on[i:i+k])
      b = sum(off[i:i+k+1])
    else:
      a += on[i+k-1]
      a -= on[i-1]
      if i+k <= len(off)-1:
        b += off[i+k]
      b -= off[i-1]
    # print (a,b)
    s = a+b
    ans = max(ans,s)
else:
  for i in range(len(on)-k+1):
    if i == 0:
      a = sum(on[i:i+k])
      b = sum(off[i:i+k])
    elif i == 1:
      a = sum(on[i:i+k])
      b = sum(off[i-1:i+k])
    else:
      a += on[i+k-1]
      a -= on[i-1]
      if i+k-1 <= len(off)-1:
        b += off[i+k-1]
      b -= off[i-2]
    s = a+b
    # print (a,b)
    ans = max(ans,s)
if ans == 0:
  print (n)
else:
  print (ans)

Buggy python submission (verdict: Runtime Error):
n, k = map(int, input().split())
s = input()

on = []
off = []

acnt = 0
bcnt = 0
for i in s:
  if i == '0':
    if bcnt > 0:
      off.append(bcnt)
      bcnt = 0
    acnt += 1
  else:
    if acnt > 0:
      on.append(acnt)
      acnt = 0
    bcnt += 1
if bcnt > 0:
  off.append(bcnt)
  bcnt = 0
if acnt > 0:
  on.append(acnt)
  acnt = 0
ans = 0
if s[0] == '1':
  for i in range(len(on)-k+1):
    s = 0
    if i == 0:
      a = sum(on[i:i+k])
      b = sum(off[i:i+k+1])
      s = a+b
    else:
      a += on[i+k-1]
      a -= on[i-1]
      b += off[i+k]
      b -= off[i-1]
      s = a+b
    # print (a,b)
    ans = max(ans,s)
else:
  for i in range(len(on)-k+1):
    if i == 0:
      a = sum(on[i:i+k])
      b = sum(off[i:i+k])
      s = a+b
      # print (sum(on[i:i+k]),sum(off[i:i+k]))
    elif i == 1:
      a = sum(on[i:i+k])
      b = sum(off[i-1:i+k])
      s = a+b
    else:
      a += on[i+k-1]
      a -= on[i-1]
      b += off[i+k-1]
      b -= off[i-1]
      #s = sum(on[i:i+k]) + sum(off[i-1:i+k])
      # print (sum(on[i:i+k]),sum(off[i-1:i+k]))
      s = a+b
    ans = max(ans,s)
if ans == 0:
  print (n)
else:
  print (ans)


Fixed submission:
n, k = map(int, input().split())
s = input()

on = []
off = []

acnt = 0
bcnt = 0
for i in s:
  if i == '0':
    if bcnt > 0:
      off.append(bcnt)
      bcnt = 0
    acnt += 1
  else:
    if acnt > 0:
      on.append(acnt)
      acnt = 0
    bcnt += 1
if bcnt > 0:
  off.append(bcnt)
  bcnt = 0
if acnt > 0:
  on.append(acnt)
  acnt = 0
ans = 0
if s[0] == '1':
  for i in range(len(on)-k+1):
    s = 0
    if i == 0:
      a = sum(on[i:i+k])
      b = sum(off[i:i+k+1])
    else:
      a += on[i+k-1]
      a -= on[i-1]
      if i+k <= len(off)-1:
        b += off[i+k]
      b -= off[i-1]
    # print (a,b)
    s = a+b
    ans = max(ans,s)
else:
  for i in range(len(on)-k+1):
    if i == 0:
      a = sum(on[i:i+k])
      b = sum(off[i:i+k])
    elif i == 1:
      a = sum(on[i:i+k])
      b = sum(off[i-1:i+k])
    else:
      a += on[i+k-1]
      a -= on[i-1]
      if i+k-1 <= len(off)-1:
        b += off[i+k-1]
      b -= off[i-2]
    s = a+b
    # print (a,b)
    ans = max(ans,s)
if ans == 0:
  print (n)
else:
  print (ans)

Buggy python submission (verdict: Runtime Error):
n, k = map(int, input().split())
s = input()

on = []
off = []

acnt = 0
bcnt = 0
for i in s:
  if i == '0':
    if bcnt > 0:
      off.append(bcnt)
      bcnt = 0
    acnt += 1
  else:
    if acnt > 0:
      on.append(acnt)
      acnt = 0
    bcnt += 1
if bcnt > 0:
  off.append(bcnt)
  bcnt = 0
if acnt > 0:
  on.append(acnt)
  acnt = 0
ans = 0
if s[0] == '1':
  for i in range(len(on)-k+1):
    s = 0
    if i == 0:
      a = sum(on[i:i+k])
      b = sum(off[i:i+k+1])
      s = a+b
    else:
      a += on[i+k-1]
      a -= on[i-1]
      b += off[i+k]
      b -= off[i-1]
      s = a+b
    print (a,b)
    ans = max(ans,s)
else:
  for i in range(len(on)-k+1):
    if i == 0:
      a = sum(on[i:i+k])
      b = sum(off[i:i+k])
      s = a+b
      # print (sum(on[i:i+k]),sum(off[i:i+k]))
    elif i == 1:
      a = sum(on[i:i+k])
      b = sum(off[i-1:i+k])
      s = a+b
    else:
      a += on[i+k-1]
      a -= on[i-1]
      b += off[i+k-1]
      b -= off[i-1]
      #s = sum(on[i:i+k]) + sum(off[i-1:i+k])
      # print (sum(on[i:i+k]),sum(off[i-1:i+k]))
      s = a+b
    ans = max(ans,s)
if ans == 0:
  print (n)
else:
  print (ans)


Fixed submission:
n, k = map(int, input().split())
s = input()

on = []
off = []

acnt = 0
bcnt = 0
for i in s:
  if i == '0':
    if bcnt > 0:
      off.append(bcnt)
      bcnt = 0
    acnt += 1
  else:
    if acnt > 0:
      on.append(acnt)
      acnt = 0
    bcnt += 1
if bcnt > 0:
  off.append(bcnt)
  bcnt = 0
if acnt > 0:
  on.append(acnt)
  acnt = 0
ans = 0
if s[0] == '1':
  for i in range(len(on)-k+1):
    s = 0
    if i == 0:
      a = sum(on[i:i+k])
      b = sum(off[i:i+k+1])
    else:
      a += on[i+k-1]
      a -= on[i-1]
      if i+k <= len(off)-1:
        b += off[i+k]
      b -= off[i-1]
    # print (a,b)
    s = a+b
    ans = max(ans,s)
else:
  for i in range(len(on)-k+1):
    if i == 0:
      a = sum(on[i:i+k])
      b = sum(off[i:i+k])
    elif i == 1:
      a = sum(on[i:i+k])
      b = sum(off[i-1:i+k])
    else:
      a += on[i+k-1]
      a -= on[i-1]
      if i+k-1 <= len(off)-1:
        b += off[i+k-1]
      b -= off[i-2]
    s = a+b
    # print (a,b)
    ans = max(ans,s)
if ans == 0:
  print (n)
else:
  print (ans)

Buggy python submission (verdict: Time Limit Exceeded):
n, k = map(int, input().split())
s = input()

on = []
off = []

acnt = 0
bcnt = 0
for i in s:
  if i == '0':
    if bcnt > 0:
      off.append(bcnt)
      bcnt = 0
    acnt += 1
  else:
    if acnt > 0:
      on.append(acnt)
      acnt = 0
    bcnt += 1
if bcnt > 0:
  off.append(bcnt)
  bcnt = 0
if acnt > 0:
  on.append(acnt)
  acnt = 0
ans = 0
if s[0] == '1':
  for i in range(len(on)-k+1):
    s = sum(on[i:i+k]) + sum(off[i:i+k+1])
    # print (sum(on[i:i+k]),sum(off[i:i+k+1]))
    ans = max(ans,s)
else:
  for i in range(len(on)-k+1):
    if i == 0:
      s = sum(on[i:i+k]) + sum(off[i:i+k])
      # print (sum(on[i:i+k]),sum(off[i:i+k]))
    else:
      s = sum(on[i:i+k]) + sum(off[i-1:i+k])
      # print (sum(on[i:i+k]),sum(off[i-1:i+k]))
    ans = max(ans,s)
if ans == 0:
  print (n)
else:
  print (ans)


Fixed submission:
n, k = map(int, input().split())
s = input()

on = []
off = []

acnt = 0
bcnt = 0
for i in s:
  if i == '0':
    if bcnt > 0:
      off.append(bcnt)
      bcnt = 0
    acnt += 1
  else:
    if acnt > 0:
      on.append(acnt)
      acnt = 0
    bcnt += 1
if bcnt > 0:
  off.append(bcnt)
  bcnt = 0
if acnt > 0:
  on.append(acnt)
  acnt = 0
ans = 0
if s[0] == '1':
  for i in range(len(on)-k+1):
    s = 0
    if i == 0:
      a = sum(on[i:i+k])
      b = sum(off[i:i+k+1])
    else:
      a += on[i+k-1]
      a -= on[i-1]
      if i+k <= len(off)-1:
        b += off[i+k]
      b -= off[i-1]
    # print (a,b)
    s = a+b
    ans = max(ans,s)
else:
  for i in range(len(on)-k+1):
    if i == 0:
      a = sum(on[i:i+k])
      b = sum(off[i:i+k])
    elif i == 1:
      a = sum(on[i:i+k])
      b = sum(off[i-1:i+k])
    else:
      a += on[i+k-1]
      a -= on[i-1]
      if i+k-1 <= len(off)-1:
        b += off[i+k-1]
      b -= off[i-2]
    s = a+b
    # print (a,b)
    ans = max(ans,s)
if ans == 0:
  print (n)
else:
  print (ans)