Buggy python submission (verdict: Runtime Error):
N = int(input())
a = list(map(int, input().split()))

a_hash = {}
for i in range(N):
    if a[i] in a_hash:
        a_hash[a[i]] += 1
    else:
        a_hash[a[i]] = 1

a_sort = sorted(a_hash.items(), key = lambda x: x[0])
a_sort = list(a_sort)
ans_list = [0] * N

if len(a) == 1:
    print(1)
    exit()

for i in range(len(a_sort)):
    if i == 0:
        if a_sort[0][0] == a_sort[1][0] - 1:
            ans_list[0] += a_sort[0][1] + a_sort[1][1]
    elif i == len(a_sort) -1:
        if a_sort[i][0] == a_sort[i-1][0] + 1:
            ans_list[i] += a_sort[i][1] + a_sort[i-1][1]
        else:
            ans_list[i] = a_sort[i][1]
    else:
        if a_sort[i][0] == a_sort[i-1][0] + 1:
            ans_list[i] += a_sort[i][1] + a_sort[i-1][1]
        if a_sort[i][0] == a_sort[i+1][0] - 1:
            ans_list[i] += a_sort[i+1][1]


print(max(ans_list))

Fixed submission:
N = int(input())
a = list(map(int, input().split()))

a_hash = {}
for i in range(N):
    if a[i] in a_hash:
        a_hash[a[i]] += 1
    else:
        a_hash[a[i]] = 1

a_sort = sorted(a_hash.items(), key = lambda x: x[0])
a_sort = list(a_sort)
ans_list = [0] * N

if len(a) == 1:
    print(1)
    exit()
if len(a_sort) == 1:
    print(a_sort[0][1])
    exit()

for i in range(len(a_sort)):
    if i == 0:
        if a_sort[0][0] == a_sort[1][0] - 1:
            ans_list[0] += a_sort[0][1] + a_sort[1][1]
    elif i == len(a_sort) -1:
        if a_sort[i][0] == a_sort[i-1][0] + 1:
            ans_list[i] += a_sort[i][1] + a_sort[i-1][1]
        else:
            ans_list[i] = a_sort[i][1]
    else:
        if a_sort[i][0] == a_sort[i-1][0] + 1:
            ans_list[i] += a_sort[i][1] + a_sort[i-1][1]
        if a_sort[i][0] == a_sort[i+1][0] - 1:
            ans_list[i] += a_sort[i+1][1]


print(max(ans_list))

Buggy python submission (verdict: Runtime Error):
N = int(input())
a = list(map(int, input().split()))

a_hash = {}
for i in range(N):
    if a[i] in a_hash:
        a_hash[a[i]] += 1
    else:
        a_hash[a[i]] = 1

a_sort = sorted(a_hash.items(), key = lambda x: x[0])
a_sort = list(a_sort)
ans_list = [0] * N

if len(a) == 1:
    print(1)
    exit()

for i in range(len(a_sort)):
    if i == 0:
        if a_sort[0][0] == a_sort[1][0] - 1:
            ans_list[0] += a_sort[0][1] + a_sort[1][1]
    elif i == len(a_sort) -1:
        if a_sort[i][0] == a_sort[i-1][0] + 1:
            ans_list[i] += a_sort[i][1] + a_sort[i-1][1]
        else:
            ans_list[i] = a_sort[i][1]
    else:
        if a_sort[i][0] == a_sort[i-1][0] + 1:
            ans_list[i] += a_sort[i][1] + a_sort[i-1][1]
        if a_sort[i][0] == a_sort[i+1][0] - 1:
            ans_list[i] += a_sort[i+1][1]


print(max(ans_list))

Fixed submission:
N = int(input())
a = list(map(int, input().split()))

a_hash = {}
for i in range(N):
    if a[i] in a_hash:
        a_hash[a[i]] += 1
    else:
        a_hash[a[i]] = 1

a_sort = sorted(a_hash.items(), key = lambda x: x[0])
a_sort = list(a_sort)
ans_list = [0] * N

if len(a) == 1:
    print(1)
    exit()
if len(a_sort) == 1:
    print(a_sort[0][1])
    exit()

for i in range(len(a_sort)):
    if i == 0:
        if a_sort[0][0] == a_sort[1][0] - 1:
            ans_list[0] += a_sort[0][1] + a_sort[1][1]
    elif i == len(a_sort) -1:
        if a_sort[i][0] == a_sort[i-1][0] + 1:
            ans_list[i] += a_sort[i][1] + a_sort[i-1][1]
        else:
            ans_list[i] = a_sort[i][1]
    else:
        if a_sort[i][0] == a_sort[i-1][0] + 1:
            ans_list[i] += a_sort[i][1] + a_sort[i-1][1]
        if a_sort[i][0] == a_sort[i+1][0] - 1:
            ans_list[i] += a_sort[i+1][1]


print(max(ans_list))