Buggy python submission (verdict: Time Limit Exceeded):
from sys import stdin

N, K = [int(x) for x in stdin.readline().rstrip().split()]
S = stdin.readline().rstrip()
cnt = 1
run = []
for i in range(1, len(S)):
    if S[i - 1] == S[i]:
        cnt += 1
    else:
        run.append(cnt)
        cnt = 1
    if i == len(S) - 1:
        run.append(cnt)
if S[0] == '0':
    run = [0] + run
if S[N - 1] == '0':
    run = run + [0]
X = [sum(run[j: j + 2 * K + 1]) for j in range(len(run) - 2 * K) if j % 2 == 0]
ans = sum(run[0: 2 * K + 1])
for j in range(2, len(run) - 2 * K):
    if j % 2 == 1:
        continue
    else:
        ans = max(ans, ans - run[j - 1] - run[j - 2] + run[j + 2 * K] + run[j + 2 * K - 1])
if len(X) == 0:
    print(N)
else:
    print(max(X))


Fixed submission:
from sys import stdin

N, K = [int(x) for x in stdin.readline().rstrip().split()]
S = stdin.readline().rstrip()
cnt = 1
run = []
if len(S) == 1:
    run.append(1)
else:
    for i in range(1, len(S)):
        if S[i - 1] == S[i]:
            cnt += 1
        else:
            run.append(cnt)
            cnt = 1
        if i == len(S) - 1:
            run.append(cnt)
if S[0] == '0':
    run = [0] + run
if S[N - 1] == '0':
    run = run + [0]
if len(run) < 2 * K + 1:
    print(sum(run))
    exit()
ans = sum(run[0: 2 * K + 1])
sb = ans
for j in range(2, len(run) - 2 * K):
    if j % 2 == 1:
        continue
    else:
        sb = sb - run[j - 1] - run[j - 2] + run[j + 2 * K] + run[j + 2 * K - 1]
        if sb > ans:
            ans = sb
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
from sys import stdin

N, K = [int(x) for x in stdin.readline().rstrip().split()]
S = stdin.readline().rstrip()
cnt = 1
run = []
for i in range(1, len(S)):
    if S[i - 1] == S[i]:
        cnt += 1
    else:
        run.append(cnt)
        cnt = 1
    if i == len(S) - 1:
        run.append(cnt)
if S[0] == '0':
    run = [0] + run
if S[N - 1] == '0':
    run = run + [0]
X = [sum(run[j: j + 2 * K + 1]) for j in range(len(run) - 2 * K) if j % 2 == 0]
if len(X) == 0:
    print(N)
else:
    print(max(X))


Fixed submission:
from sys import stdin

N, K = [int(x) for x in stdin.readline().rstrip().split()]
S = stdin.readline().rstrip()
cnt = 1
run = []
if len(S) == 1:
    run.append(1)
else:
    for i in range(1, len(S)):
        if S[i - 1] == S[i]:
            cnt += 1
        else:
            run.append(cnt)
            cnt = 1
        if i == len(S) - 1:
            run.append(cnt)
if S[0] == '0':
    run = [0] + run
if S[N - 1] == '0':
    run = run + [0]
if len(run) < 2 * K + 1:
    print(sum(run))
    exit()
ans = sum(run[0: 2 * K + 1])
sb = ans
for j in range(2, len(run) - 2 * K):
    if j % 2 == 1:
        continue
    else:
        sb = sb - run[j - 1] - run[j - 2] + run[j + 2 * K] + run[j + 2 * K - 1]
        if sb > ans:
            ans = sb
print(ans)

Buggy python submission (verdict: Runtime Error):
rom sys import stdin

N, K = [int(x) for x in stdin.readline().rstrip().split()]
S = stdin.readline().rstrip()
cnt = 1
run = []
for i in range(1, len(S)):
    if S[i - 1] == S[i]:
        cnt += 1
    else:
        run.append(cnt)
        cnt = 1
    if i == len(S) - 1:
        run.append(cnt)
X = [sum(run[j: j + 2 * K + 1]) for j in range(max(len(run) - 2 * K, 1))]
if len(X) == 0:
    print(1)
else:
    print(max(X))


Fixed submission:
from sys import stdin

N, K = [int(x) for x in stdin.readline().rstrip().split()]
S = stdin.readline().rstrip()
cnt = 1
run = []
if len(S) == 1:
    run.append(1)
else:
    for i in range(1, len(S)):
        if S[i - 1] == S[i]:
            cnt += 1
        else:
            run.append(cnt)
            cnt = 1
        if i == len(S) - 1:
            run.append(cnt)
if S[0] == '0':
    run = [0] + run
if S[N - 1] == '0':
    run = run + [0]
if len(run) < 2 * K + 1:
    print(sum(run))
    exit()
ans = sum(run[0: 2 * K + 1])
sb = ans
for j in range(2, len(run) - 2 * K):
    if j % 2 == 1:
        continue
    else:
        sb = sb - run[j - 1] - run[j - 2] + run[j + 2 * K] + run[j + 2 * K - 1]
        if sb > ans:
            ans = sb
print(ans)